I 


COMPENDIOUS    SYSTEM 
o  P 

Mineralogy  &  Metallurgy; 


tXTRACTED  FROM 


THE  AMERICAN  EDITION 


O  F 


THE    ENCYCLOPAEDIA, 


N  OW    PUBLISHING 


BT     r HO  MAS    DOBS01\r, 


,0 


AT  THE    STONE-HOUSE,  Nu  41,    SOUTH    SECOND-S-TRFT. 
M  DCC,XC1V. 


CONTENTS. 

Page. 

INTRODUCTION  i 

PART     I. 

Of  Experiments  upon  Earth  and  Stones,  2 

Experiments  upon  Metals  and  Ores,  1 4 
Description  of  a  portable  JLabaratory  for 

a/faying  Minerals,                                 •  3^ 

PART     IL 

ARRANGEMENT  of  MINERAL  BODIES,  41 

CLASS  I.                       EARTHS,          -  -4.2 

Order         I.   Calcareous  Earths,             -  43 

IT.   Ponderous  Earths  ^  60 

III.  Magnefian  Earths,            -           -  62 

IV.  Siliceous  Earthy           -              . '  68 
V.  Argillaceous  Earth,          -         -  101 

CLASS     II.                    SALTS,        -  108 

Qrdir         I.  Acid  Salts                -                -  1 09 

II.  Alkaline  Salts,  HO 

III.  Neutral  Salts,              -              -  118 

IV.  Earthy  Neutral  Salts,                -  1 28 
V.  Metallic  Salts,                             -  138 

VI.   Triple  Salts,  144 

CEASS  III.     MINERAL  INFLAMMABLE   SUB 
STANCES  148 
CLASS    IV.       METALLIC  SUBSTANCES,  184 

Order         I.  Noble  or  P  erf  eft  Metals,  188 

II.  LnperfeS  or  Bafe  Metals,  2io 

III.  Semimetals,               -  239 

A  2  AJPEM- 


iv  CONTENTS. 

Page. 

APPENDIX.   Of  Saxa  and  Petrifactions,  .  266 

Order        I.          Saxa  *  -  ib. 

II.  Mineral  Changes  or  Petrifactions,  306 

III.    Volcanic  Produces,          -  -  310 

METALLURGY,  323 

Part  I.      Seel.       I.  Of  Metals  aud  Metallization,  324 

II.         Mines  and  Ores  in  general,  343 

III.  Pyrites,  347 

IV.  E/aying  Ores  in  general,  355 
Part  II.      Containing  a  Swnmary  Defer  iption  of 

the  Principal  Ores  of  each  Metal, 
and  the  Method  of  E/aying  them. 

St5t.         I.  Ores  of  Gold,  360 

II.            of Platina,  363 

III.  of  Silver,                   -  '        -           364- 

IV.  of  Copper,              -  405 
V.            of  Lead,  420 

VI.  of  Tin,  -  423 

VII.  of  Iron,  -  -  425 

VIII.  of  Mercury,  432 

IX.  of  the  Regulus  of  Antimony,  434 

X.  of Bifmuth,  437 

XL  of  the  Regulus  of  Cobalt,  .       -         438 

XII.  of  Zinc,  -  443 

XIII.  of Arfenic,  443 

Part  III.  Smelting  of  Ores,  445 

Stfl.         I.  Extraction  of  Sulphur  from  Pyrites 

and  other  Minerals, 
H.  Smelting  of  Ores  in  general, 

III.  of  Ores  of  Silver, 

IV.  of  Ores  of  Copper, 
V.  of  Ores  of  Iron, 

VI.  of  Tin  Ores, 

VII.  of  Ores  of  Lead, 

VIII.  Ores  of  the  Semimctals, 


MINERALOGY. 


M: 


.INERALOGY  is  thatfcience  which  teaches 
us  the  properties  of  mineral  bodies,  and  by  which  we 
learn  how  to  character ife,  diftinguifh,  and  clafs  them 
into  a  proper  order. 

INTRODUCTION. 

MINERALOGY  feems  to  have  been  in  a  manner  co 
eval  with  the  world*  Precious  ftones  of  various  kinds 
appear  to  have  been  well  known  among  the  Jews  and 
Egyptians  in  the  time  of  Mofes ;  and  even  the  moil 
rude  and  barbarous  nations  appear  to  have  had  fome 
knowledge  of  the  ores  of  different  metals.  As  the 
fcience  is  nearly  allied  to  chemiftry,  it  is  probable  that 
the  improvements  both  in  chemiftry  and  mineralogy 
have  nearly  kept  pace  with  each  other  ;  and  indeed  it 
is  but  of  late,  fmce  the  principles  of  chemiftry  were 
well  underftood,  that  mineralogy  has  been  advanced 
to  any  degree  of  perfection.  The  beft  way  of  ftudy- 
ing  mineralogy,  therefore,  is  by  applying  chemiftry  to 
it ;  and  not  contenting  ourfelvcs  merely  with  infpecl- 
ing  the  outfides  of  bodies,  but  decompounding  them 
according  to  the  rules  of  chemiftry,  This  method 
has  been  brought .  to  the  greateft  perfection  by  Mr 
Pott  of  Berlin,  and  after  him  by  Mr  Cronftedt  of 
B  Sweden* 


C     *     ] 

Sweden.  To  obtain  this  end,  chemical  experiments 
in  the  large  way  are  without  doubt  neceffkry  :  but  as 
a  great  deal  of  the  mineral  kingdom  has  already  been 
examined  in  this  manner,  we  do  not  need  to  repeat 
all  thofe  experiments  in  their  whole  extent,  unlefs 
fome  new  and  particular  phenomena  fhould  difcover 
themfelves  in  thofe  things  we  are  examining ;  elfe  the 
tedioufnefs  of  thofe  proceffes  might  difcourage  fome 
from  going  farther,  and  take  up  much  of  the  time  of 
others  that  might  be  better  employed.  An  eafier 
way  may  therefore  be  adopted,  which  even  for  the 
mod  part  is  fufficient,  and  which,  though  made  in 
miniature,  is  as  fcientifical  as  the  common  manner 
of  proceeding  in  the  laboratories,  fince  it  imitates 
tha%  and  is  founded  upon  the  fame  principles.  This 
confifts  in  making  the  experiments  upon  a  piece  of 
charcoal  with  the  concentrated  flame  of  a  candle 
directed  through  a  blow-pipe.  The  heat  occafioned  by 
this  is  very  intenfe  ;  and  the  mineral  bodies  may  here 
be  burnt,  calcined,  melted  and  fcorified,  &c.  as  well 
as  in  any  great  works. 

For  a  defcription  of  the  blow-pipe,  the  method  of 
tifing  it,  the  proper  fluxes  to  be  employed,  and  the 
different  fubjscls  of  examination  to  which  that  inftru- 
ment  is  adapted,  fee  the  article  Biotr-pipe,  where  all 
thofe  particulars  are  concifely  detailed.  It  may  not 
be  improper  here,  however,  to  refume  thofe  details  at 
greater  length  ;  avoiding,  at  the  fame  time,  all  unne- 
ceffary  repetitions.  After  which  we  (hall  exhibit  a 
fcientific  arrangement  of  the  mineral  kingdom  accord 
ing  to  the  mo  ft  approved  fyftem. 


PART  L 


C     3     ] 
PART     I. 

EXPERIMENTAL  MINERALOGY ; 

WITH    A 

DESCRIPTION  OF  THE  NECESSARY  APPARATUS '*. 


SECTION    I. 
Of  experiments  upon  Earths  an:d  Stones. 

VV  HEN  any  of  thefe  fubftances  are  to  be  tried,  we 
muft  not  begin  immediately  with  the  blow-pipe  ;  but 
fome  preliminary  experiments  ought  to  go  before,  by 
which  thofe  in  the  fire  may  afterwards  be  directed. 
For  inftance,  a  (tone  is  not  always  homogenous,  or  of 
the  fame  kind  throughout,  although  it  may  appear  to 
the  eye  to  be  fo.  A  magnifying  glafs  is  therefore  ne- 
ceflary  to  difcover  the  heterogeneous  particles,  if  there 
be  any  ;  and  thefe  ought  to  be  feparated,  and  every 
part  tried  by  itfelf,  that  the  efrecis  of  two  different 
things,  examined  together,  may  not  be  attributed  to 
or.e  alone.  This  might  happen  with  fome  of  the  finer 
mics,  which  are  now  and  then  found  mixed  with  fmall 
particles  of  quartz,  fcarcely  to  be  perceived  by  the  eye 
The  trapp  (in  German  fchwartzftein)  is  alfo  fometimes 

*  From  Enjrerftrom's  Treatife  on  the  Blow- pipe,  and  Magel 
lan's  Defcription  of  Pocket-Laboratories,  &c.  fubjoined  to  the 
En<rlifh  Translation  of  Croniledt's  Minerdogy,  ad  edit  in  a  vols. 
Pilly. 

B  2  mixed 


3     4     1 

mixed  with  very  fine  particles  of  feltfpar  (fpatam  fcin- 
-tittans)  or  of  calcareous  fpar,  &c.  After  this  expe 
riment,  the  hardnefs  of  the  (tone  in  queft  ion  muft  be 
tried  with  fteel.  The  flint  and  garnets  are  com 
monly  known  to  ftrike  fire  with  fteel ;  but  there 
are  alfo  other  ftones,  which,  though  very  feldom,  are 
found  fo  hard  as  likewife  to  ftrike  fire.  There  is  a 
kind  of  trapp  of  that  ha.rdnefs,  in  which  no  particles 
of  feltfpar  are  to  be  feen.  Coloured  glaffes  refemble 
true  gems ;  but  as  they  are  very  foft  in  proportion  to 
thefe,  they  are  eafily  difcovered  by  means  of  the  file. 
The  common  qaartz-cryftals  are  harder  than  coloured 
glaffes,  but  fofter  than  the  gems.  The  loadftone  dif- 
covers  the  prefence  of  iron,  when  it  is  not  mixed  in  too 
fmall  a  quantity  in  the  ftone,  and  often  before  the  ftone 
is  roafted.  Some  kinds  of  haematites,  and  particularly 
the  ccerulefcens,  greatly  refemble  fome  other  iron  ores; 
but  this  diftinguifhes  itfelf  from  them  by  a  red  colour 
when  pounded,  the  others  giving  a  blackifh  powder, 
and  fo  forth. 

The  management  of  the  Btow-pipe'h'a.s  beendefcribed 
under  that  article  ;  but  ?  few  particulars  may  be  here 
recapitulated,  or  added. 

The  candle  ought  to  be  fnuffed  often,  but  fo  that 
the  top  of  the  wick  may  retain  fome  fat  in  it,  becaufe 
the  flame  is  not  hot  enough  when  the  wick  is  almoft 
burnt  toaflies;  but  only  the  top  muft  be  fnuffed  off, 
becaufe  a  low  wick  gives  too  fmal!  a  flame.  The  blue 
flame  is  the  hotteft ;  this  ought,  therefore,  to  be 
forced  out  when  a  great  heat  is  required,  and  only  the 
point  of  the  flame  muft  be  directed  upon  the  fubje<5l 
which  is  to  be  effayed.  M.  Magellan  recommends,  as 
being  moft  cleanly  and  convenient,  that  the  candle  be 
made  of  wax,  and  the  wick  fhould  be  thicker  than  or 
dinary.  Its  upper  end  muft  be  bended  towards  ihe 
matter  intended  to  be  heated,  and  the  ftream  of  air 
muft  be  directed  along  the  furface  of  the  bended  part, 
fo  as  not  abfolutely  to  touch  it. 

The 


C    5    3 

The  piece  of  charcoal  made  ufe  of  in  thefe  expe 
riments  muft  not  be  of  a  difpofition  to  crack.  If  this 
Ihould  happen,  it  muft  gradually  be  heated  until  it 
does  not  crack  any  more,  before  any  afTay  is  made  up 
on  it.  If  this  be  not  attended  to,  but  the  affay  made 
immediately  with  a  ftrong  flame,  fmall  pieces  of  it  will 
fplit  off  in  the  face  and  eyes  of  the  aiTayer,  and  often 
throw  along  with  them  the  matter  that  was  to  be  af- 
fayed.  Charcoal  which  is  too  much  burnt  confumes 
too  quick  during  the  experiment,  leaving  fmall  holes 
in  it,  wherein  the  matter  to  be  tried  may  be  loft ;  and 
charcoal  that  is  burnt  too  little,  catches  flame  from 
the  candle,  burning  by  itfelf  like  a  piece  of  wood, 
which  likewife  hinders  the  procefs. 

Of  thofe  things  that  are  to  be  afTayed,  only  a  fmall 
piece  muft  be  broken  off  for  that  purpofe,  not  bigger 
than  that  the  flame  of  the  candle  may  be  able  to  act 
upon  it  at  once,  if  required ;  which  is  fometimes  ne- 
ce/Tary,  as,  when  the  matter  requires  to  be  made 
red  hot  throughout,  the  piece  ought  to  be  broken  as 
thin  as  poffible,  at  leaft  the  edges ;  the  advantage  of 
which  is  obvious,  the  fire  having  then  more  influence 
upon  the  fubjeft,  and  the  experiment  being  more 
quickly  made. 

Some  of  tiie  mineral  bodies  are  very  difficult  to  be 
kept  fteady  upon  the  charcoal  during  the  experiment, 
before  they  are  made  red  hot ;  becaufe,  as  foon  as  the 
flame  begins  to  aft  upon  them,  they  fplit  afunder  with 
violence,  and  are  difperfed.  Such  often  are  thofe  which 
are  of  a  foft  confidence  or  a  particular  figure,  and 
which  prefer ve  the  fame  figure  in  however  minute  par 
ticles  they  are  broken  ;  for  inftance,  the  calcareous  fpar, 
the  fparry  gypfum,  fparry  fluor,  white  fparry  lead- 
ore,  the  potters  ore,  the  teffellatcd  mock-lead  or 
blende,  &c.  even  all  the  common  fluors  which  have  no 
determinate  figure.  Thefe  not  being  fo  compact  as 
common  hard  ftones,  when  the  flame  is  immediately 
urged  upon  them,  the  heat  forces  itfelf  through  and 
B  3 


[     <5     3 

in':o  their  clefts  or  pores,  and  caufes  this  violent  ex- 
panfion  and  difperfion.  Many  of  the  clays  are  like- 
wife  apt  to  crack  in  the  fire,  which  may  be  for  the 
moil  part  afcribed  to  the  humidity,  of  which  they  al 
ways  retain  a  portion. 

The  only  way  of  preventing  this  inconvenience  is 
to  heat  the  body  as  flowly  as  poffible.  It  is  bed,  fird 
of  all,  to  heat  that  place  of  the  charcoal  where  the 
piece  is  intended  to  be  put  on  ;  and  afterwards  lay  it 
thereon ;  a  little  crackling  will  then  enfue,  but  com- 
monly  of  no  great  confequence.  After  that  the  flame 
is  to  be  blown  very  flowly  towards  it,  in  the  beginning 
not  directly  upon,  but  fomewhat  above  it,  and  fo  ap 
proaching  nearer  and  nearer  with  the  flame  until  it 
become  red  hot.  This  will  do  for  the  mod  part ; 
but  there  are  neverthelefs  fome,  which,  notwithltand- 
ing  all  the  precautions,  it  is  almoft  impoflible  to 
keep  on  the  charcoal.  Thus  the  fluors  are  generally 
the  mod  difficult ;  and  as  one  of  their  principal  ch.i- 
raclers  is  difcovered  by  their  effects  in  the  fire  per  fe, 
they  ought  necefTarily  to  be  tried  that  way.  To  this 
purpofe,  it  is  bed  to  make  a  little  hole  in  the  charcoal 
to  put  the  fluor  in,  and  then  to  put  another  piece  of 
charcoal  as  a  covering  upon  this,  leaving  only  a  fmall 
opening  for  the  flame  to  enter.  As  this  ft  one  will  never- 
thelefs  fplit  and  fly  about,  a  larger  piece  thereof  than  is 
before-mentioned  mud  be  taken,  in  order  to  have  atlead 
fomething  of  it  left. 

But  if  the  experiment  is  to  be  made  upon  a  done 
whofe  effe&s  one  does  not  want  to  fee  in  the  fire  per  fe, 
but  rather  with  fluxes,  then  a  piece  of  it  ought  to  be 
forced  down  into  melted  borax,  when  always  fome 
part  of  it  will  remain  in  the  borax,  notwithdanding  the 
greated  part  may  fometimes  fly  away  by  cracking. 

I.  Offubjlances  t&  be  tried  in  tbejlre  per  fe.  As  the 
ftones  undergo  great  alterations  when  expofed  to  the 
fire  by  them  (elves,  whereby  fome  of  their  characlerif- 
ticks,  and  often  the  mod  principal,  are  difcovered, 

they 


[     7     ] 

they  ought  fird  to  be  tried  that  way,  obferving  what 
has  been  faid  before  concerning  the  quantity  of  mat 
ter,  direction  of  the  fire,  £c.  The  following  are  ge 
nerally  the  refults  of  this  experiment. 

Calcareous  earth  or  Jlom,  when  it  is  pure,  does  not 
melt  by  itfelf,  but  becomes  white  and  friable,  fo  as  to 
break  freely  between  the  fingers  ;  and,  if  fuffered  to 
cool,  and  then  mixed  with  water,  it  becomes  hot,  juft 
like  common  quick-lime.  As  in  thefe  experiments 
only  very  fmall  pieces  are  ufed,  this  laft  effect  is  bed 
difcovered  by  putting  the  proof  on  the  outfide  of  the 
hand,  with  a  drop  of  water  to  it,  when  inftantly  a 
very  quick  heat  is  felt  on  the  fkin.  When  the  calca 
reous  fubftance  is  mixed  with  the  vitriolic  acid,  as  in 
gypG'rn,  or  with  a  clay,  as  in  marie,  it  commonly 
melts  by  itfelf,  yet,  more  or  lefs  difficultly  in  propor 
tion  to  the  differences  of  the  mixtures.  Gypfum  pro 
duces  generally  a  white,  and  marie  a  grey,  glafs 
or  flag.  When  there  is  any  iron  in  it,  as  a  white 
iron  ore,  it  becomes  dark,  and  fometimes  quite  black, 
&c. 

The  Ji/icia  never  melt  alone,  but  become  generally 
more  brittle  after  being  burnt.  Such  of  them  as  are 
coloured  become  colourlefs,  and  the  fooner  when  it 
does  not  arife  from  any  contained  metal ;  for  inftance, 
the  topazes,  amethifts,  £c.  fome  of  the  precious  ftones, 
however,  excepted :  And  fuch  as  are  mixed  with  a 
quantity  of  iron  grow  dark  in  the  fire,  as  fome  of  the 
jafpers,  &c. 

Garnets  melt  always  into  a  black  flag,  and  fometimes 
fo  eafily  that  they  may  be  brought  into  a  round  glo 
bule  upon  the  charcoal. 

The  aroillacea,  when  pure,  never  melt,  but  become 
white  and  hard.  The  fame  effects  follow  when  they 
are  mixed  with  phlogifton.  Thus  the  foap-rock 
is  eafily  cut  with  the  knife  ;  but  being  burnt  it  cuts 
glafs,  and  would  ftrike  fire  with  the  fteel,  if  as  large 
a  piece  as  is  neceifary  for  that  purpofe  could  be  tried 

in 


C     8     ] 

in  this  way.  The  foap-rocks  are  fometlmes  found  of 
a  dark  brown  and  nearly  black  colour,  but  neverthelefs 
become  quite  white  in  the  fire  like  a  piece  of  China 
ware.  However,  care  muft  be  taken  not  to  urge  the 
flame  from  the  top  of  the  wick,  there  being  for  the 
inoft  part  a  footy  fmoke,  which  commonly  will  darken 
all  that  it  touches  ;  and  if  this  is  not  obferved,  a  mif- 
take  in  the  experiment  might  eafily  happen.  But  if 
it  is  mixed  with  iron,  as  it  is  fometimes  found,  it  does 
not  fo  eafily  part  with  its  dark  colour..  The  argillaceas 
when  mixed  with  lime  melt  by  themfelves,  as  above- 
mentioned.  When  mked  with  iron,  as  in  the  boles, 
they  grow  dark  or  black  ;  nnd  if  the  iron  is  not  in  too 
great  a  quantity,  they  melt  alone  into  a  dark  flag ; 
the  fame  happens  when  they  are  mixed  with  iron  and 
a  little  of  the  vitriolic  acid,  as  in  the  common  clay,  &c. 

Mica  and  ajbejlos  become  fomewhat  hard  and  brittle 
in  the  fire,  and  are  more  or  lefs  refractory,  though 
they  give  fome  marks  of  fufibility. 

Thej^W-j-  difcover  one  of  their  chief  characteriftics 
by  giving  a  light  like  phofphorus  in  the  dark,  when 
they  are  flowly  heated;  but  lofe  this  property,  as  well 
as  their  colour,  as  foon  as  they  are  made  red  hot. — 
They  commonly  melt  in  the  fire  into  a  white  opaque 
flag,  though  fome  of  them  not  very  eafily. 

Some  forts  of  the  zeolites  melt  eafily,  and  foam  in  the 
fire,  fometimes  nearly  as  much  as  borax,  and  become  a 
frothy  fl:ig,  &c. 

A  great  many  of  thofe  mineral  bodies  which  are  im 
pregnated  with  iron,  as  the  boles,  and  fome  of  the 
white  iron  ores,  &c.  as  well  as  fome  of  the  other  iron 
eres,  viz.  the  bloodftone,  are  not  attracted  by  the 
loadftone  before  they  have  been  thoroughly  roafted,  &c. 

2.  Of  fubftances  heated  with  Jinxes.  Alter  the  mine 
ral  bodies  have  been  tried  in  the  fire  by  themfelves, 
they  ought  to  be  heated  with  fluxes  to  difcover  if 
they  can  be  melted  or  not,  and  fome  other  phenomena 
attending  this  operation.  For  this  purpofe,  three  dif 
ferent 


ferent  kinds  of  falts  are  ufed  as  fluxes,  viz.  fal  foday 
borax,  and  fal  fufible  microfmicum ;  (fee  the  article 
Bi.ow-Pipe). 

The  fal  foda  is,  however,  not  much  ufed  in  thefe 
fmall  experiments,  its  effects  upon  the  charcoal  render 
ing  it  for  the  moft  pan  unfit  for  it ;  becaufe,  as  foon 
as  the  flame  begins  to  act  upon  it,  it  melts  inftantly, 
and  is  almoft  wholly  abforbed  by  the  charcoal.  When 
this  fait  is  employed  to  make  any  experiment,  a  very 
little  quantity  is  wanted  at  once,  viz.  about  the  cubical 
contents  of  an  eighth  part  of  an  inch,  more  or  lefs. 
This  is  laid  upon  the  charcoal,  and  the  flame  blown 
on  it  with  the  blow-pipe ;  but  as  this  fait  commonly 
is  in  form  of  a  powder,  it  is  neceffary  to  go  on  very 
gently,  that  the  force  of  the  flame  may  not  difperfe 
the  minute  particles  of  the  fait.  As  foon  as  it  begins 
to  melt,  it  runs  along  on  the  charcoal,  almoft  like  melc- 
ed  tallow  ;  and  when  cold,  it  is  a  glafly  matter  of  an 
opaque  dull  colour  fpread  on  the  coal.  The  moment 
it  is  melted,  the  matter  which  is  to  be  tried  ought  to 
be  put  into  it,  becaufe  otherwife  the  greateft  part  of 
the  fait  will  be  foaked  into  the  charcoal,  and  too  little 
of  it  left  for  the  intended  purpofe.  The  flame  ought 
then  to  be  directed  on  the  matter  itfelf ;  and  if  the  fait 
fpreads  too  much  about,  leaving  the  proof  almoft  alone, 
it  may  be  brought  to  it  again  by  blowing  the  flame  on 
its  extremities,  and  directing  it  towards  the  fubject  of 
the  experiment.  In  the  aflays  made  with  this  fait,  it  is 
true,  we  may  find  whether  the  mineral  bodies  which  are 
melted  with  it  have  been  diflblved  by  it  or  not :  but 
we  cannot  tell  with  any  certitude  whether  this  is  done 
haftily  and  with  force,  or  gently  and  flow  ;  nor  whe 
ther  a  lefs  or  a  greater  part  of  the  matter  has  been 
diflblved :  neither  can  it  be  well  diftinguiihed  if  the  mat 
ter  has  imparted  any  weak  tincture  to  the  flag  ;  be 
caufe  this  fait  always  bubbles  upon  the  charcoal  during 
the  experiment,  nor  is  it  clear  when  cool ;  fo  that 


C     10     ] 

fcarcely  any  colour,  except  it  be  a  very  deep  one,  can 
be  difcovered,  although  it  may  fometimes  be  coloured 
by  the  matter  that  has  been  tried. 

The  following  earths  are  entirely  folnlle  in  this  flux 
with  effervefcence  :  Agate  ;  chalcedony  ;  carnelian  ; 
Turkey  ftone  f ,  (cos  'Turcica)  ;  fluor  mineralis  -j-  ; 
onyx  ;  opal ;  quartz  ;  common  flint ;  ponderous  fpar. 
The  following  are  divifible  in  it  with  or  without  effer 
vefcence,  but  not  entirely  foluble  :  Amianthus  ;  af- 
bertus  ;  bafaltes  ;  chryfolite  \  ;  granate  \  ;  hornblende  ; 
jafper;  marlftone  ;  mica;  the  mineral  of  alum  from 
Tolfa  5  petrofilex  ;  aluminous  flate  and  roof  (late  from 
Helfmgia  ;  emeralds  ,  fteatites  ;  common  flint ;  fchoerl; 
talc  ;  trapp  ;  tripoli ;  tourmalin.  And  the  following 
are  neither  fufible  nor  diviiible  in  it :  Diamond  j  hy 
acinth  ;  ruby  ;  fapphire  ;  topaz. 

The  other  two  falts,  viz.  borax  and  the  fa!  microcof- 
muurn,  are  very  well  adapted  to  thefe  experiments,  be- 
caufe  they  may  by  the  flame  be  brought  to  a  clear  un- 
coloured  and  tranfparent  glafs ;  and  as  they  have  no 
attraction  to  the  charcoal,  they  keep  themfelves  always 
upon  it  in  a  round  globular  form.  The  fal  fufible  mi- 
crocofmicum  §  is  very  fcarce,  and  perhaps  not  to  be 
met  with  in  the  fhops  ;  it  is  made  of  urine. 

The  following  earths  are  foluble  in  borax,  with  more 
or  lefs  effervefcence  :  Fluor  mineralis  f  ;  marie  ;  mica  f  ; 
the  mineral  of  alum  from  Tolfa  ;  aluminous  flate,  and 
roof-flate  from  Helfmgia  f  ;  ponderous  fpar  ;  fchoerl  ; 
talc  f  ;  tourmalin.  And  the  following  without  effer- 
vefcence  ;  Agate  ;  diamond  ;  amianthus  ;  afbeftus  ;  bi- 
faltes  ;  chalcedony  ;  carnelian  ;  chryfolite  ;  cos  turcica  ; 
granate  ;  hyacinth  *  ;  jafper  ;  lapis  ponderofus  ;  onyx  ; 
opal ;  petro-iilex  ;  quartz  *  ;  ruby  ;  fapphire  ;  com 
mon  flint  *  ;  fteaute  ;  trapp ;  trippel,  or  tripoli ; 
topaz  ;  zeolite  ;  hydrophanes. 

in  the  microcofmic  fait,  the  following  are  foluble 
with  more  or  lefs  effervefcence ;  Bafaltes  f ;  turkey 

(lone 


C    "    ] 

ft  one  £  ;  fluor  mineralis  -}• ;  marie  ;  mica  ;  the  mineral  of 
alum  from  Tolfa ;  fchiftus  aluminaris,  fchiflus  tegula- 
lis  from  Mdfmgiaf  ;  fchoerl ;  fpathum  ponderofum  ; 
tourmalin  f  ;  lapis  ponderofus.  And  the  following 
without  viable  effervefcence  :  Agate  ;  diamond  ;  ami 
anthus  ;  aibeftus  ;  chalcedony  ;  carnelian  ;  chryfolite  ; 
granate;  hyacinth;  jafper;  onyx  || ;  opal;  petrofi- 
lex  ;  quartz  II  ;  ruby  ;  fapphire  ;  common  flint  [|  ; 
emerald  ;  talc  ;  topaz  ;  trapp  ;  trippel ;  zeolite  ;  horn- 
blend  ;  hydrophanes  ;  lithomarga  ;  fteatites. 

Calcareous  earth,  ponderous  fpar,  gypfum,  and 
other  additaments,  often  uffitl  the  folution,  as  well  in 
the  microcofmic  fait  as  in  borax.  To  which  it  is  ne- 
ceflary  to  add,  that  in  order  to  obferve  the  effervef 
cence  properly,  the  matter  added  to  the  flux  fhould 
be  in  the  form  of  a  fmall  particle  rather  than  in  fine 
powder  ;  becaufe  in  this  laft  there  is  always  air  between 
the  particles,  which  being  afterwards  driven  off  by 
the  heat  afford  the  appearance  of  a  kind  of  effervef 
cence  (A). 

The  quantity  of  thofe  two  falts  required  for  an  ex 
periment  is  almoft  the  fame  as  thefa/fod<e  ;  but  as  the 
former  are  cryftallifed,  and  consequently  include  a 
great  deal  of  water,  particularly  the  borax,  their  bulk 
is  confiderably  reduced  when  melted,  and  therefore  a 
little  more  of  them  may  be  taken  than  the  before  men 
tioned  quantity. 

Both  thofe  falts,  efpecially  the  borax,  when  ex- 
pofed  to  the  flame  of  the  blow-pipe,  bubble  very 
much  and  foam  before  they  rnelr  to  a  clear  glafs, 
which  for  the  mod  part  depends  on  the  water  they 


(A)  In  the  above  lifts,  the  articles  marked  f  effer- 
vefce  very  little  ;  thofe  marked  f  not.  at  all ;  thofe  mark 
ed  *  require  a  larger  quantity  of  the  flux  and  a  longer 
continuance  of  heat  than  the  reft ;  thofe  marked  ||  are 
more  difficultly  diiTolved  than  the  others. 

contain. 


contain.  And  as  this  would  hinder  the  aflkyer  from 
making  due  obfervations  on  the  phenomena  of  the  ex 
periment,  the  fait  which  is  to  be  ufed  muft  firft  be 
brought  to  a  clear  glafs  before  it  can  ferve  as  a  flux  \ 
it  muft  therefore  be  kept  in  the  fire  until  it  become 
fo  tranfparent  that  the  cracks  in  the  charcoal  may  be 
ieen  through  it.  This  done,  whatfoever  is  to  be  tried 
is  put  to  it,  and  the  fire  continued. 

Here  it  is  to  be  obferved,  that  for  the  afTays  made 
with  any  of  thefe  two  fluxes  on  mineral  bodies,  no 
larger  pieces  muft  be  taken  than  that  altogether  they 
may  keep  a  globular  form  upon  the  charcoal ;  becaufe 
it  may  then  be  better  diftinguifhed  in  what  manner 
the  flux  acts  upon  the  matter  during  the  experiment. 
If  this  be  not  obferved,  the  flux,  communicating  itfelf 
with  every  point  of  the  furface  of  the  mineral  body, 
fpreads  all  over  it,  and  keeps  the  form  of  this  laft, 
which  commonly  is  flat,  and  by  that  means  hinders  the 
operator  obferving  all  the  phenomena  v  hich  may  hap 
pen.  Befides,  the  flux  being  in  too  fmall  a  quantity 
in  proportion  to  the  body  to  be  tried,  will  be  too  weak 
to  act  with  all  its  force  upon  it.  The  beft  proportion 
therefore  is  about  a  third  part  of  the  mineral  body  to 
the  flux  ;  and  as  the  quantity  of  the  flux  abovemen- 
tioned  makes  a  globe  of  a  due  fize  in  regard  to  the 
greateft  heat  that  is  poffible  to  procure  in  thefe  expe 
riments,  fo  the  fize  of  the  mineral  body  muft  be  a 
third  part  lefs  here  than  when  it  is  to  be  tried  in  the 
fire  by  itfelf. 

Thefalfoct*,  as  has  been  already  obferved,  is  not  of 
much  ufe  in  thefe  experiments  ;  nor  has  it  any  partU 
cular  qualities  in  preference  to  the  two  laft  mentioned 
falts,  except  that  it  diifolves  the  zeolites  eafier  than 
they  do. 

The  microcofmic  fait  fhows  almoft  the  fame  effects  in 
the  fire  as  the  borax,  only  differing  from  it  in  a  very  few 
circumftances ;  of  which  one  of  the  principal  is,  that, 
when  melted  with  manganefe,  it  becomes  of  a  crim- 

iba 


C    13    ] 

fon  hue  inftead  of  a  jacinth  colour,  which  borax  takes. 
This  fait  is,  however,  for  its  fcarcity  Mill  very  little  in 
life,  borax  alone  being  that  which  is  commonly  employ- 
ed.  Whenever  a  mineral  body  is  melted  with  any  of 
thefe  two  laft  mentioned  falts,  in  the  manner  already 
defcribed,  it  is  eafily  feen,  Whether  it  quickly  diffolves  ; 
in  which  cafe  an  effervefcence  arifes,  that  lafts  till  the 
whole  be  difiblved  :  Whether  the  folution  be  (lowly 
performed  ;  in  which  cafe  few  and  fmall  bubbles  only 
rife  from  the  matter :  or,  Whether  it  can  be  diifolved 
at  all ;  becaufe  if  not,  it  is  obferved  only  to  turn  round 
in  the  flux,  without  the  leaft  bubble,  and  the  edges 
look  as  fharp  as  they  were  before. 

In  order  farther  to  illuftrate  what  has  been  faid  about 
thefe  experiments,  we  fhall  give  a  few  examples  of  the 
effects  of  borax  upon  the  mineral  bodies.— The  calca 
reous  fubftances,  and  all  thofe  ftones  which  contain  any 
thing  of  lime  in  their  compofition,  di/Tolve  readily  and 
with  effervefcence  in  the  borax.  The  effervefcence  is 
the  more  vielent  the  greater  the  portion  of  lime  contain 
ed  in  the  (lone.  This  caufe,  however,  is  not  the  only 
one  in  the  gypfum,  becaufe  both  the  constituents  of 
this  do  readily  mix  with  the  borax,  and  therefore  a 
greater  effervefcence  arifes  in  melting  gypfum  with  the 
borax  than  lime  alone. — The  Jilicea  do  not  diflblve  ; 
fome  few  excepted  which  contain  a  quantity  of  iron. — 
The  argillacea!)  when  pure,  are  not  acted  upon  by  the 
borax  :  but  when  they  are  mixed  with  fome  heteroge 
neous  bodies,  they  are  diffclved,  though  very  flowly  ; 
fuch  are,  for  initance,  the  ftone-marrow,  the  common 
clay,  &c.  % 

The  granatesj  zeolites,  and  frapp,  difTolve  but  flowly. 
Thej^ttcrj-,  ajbeflintf,  and  micacea9  diffolve  for  the  moil 
part  very  eafily  ;  and  fo  forth.— Some  of  thefe  bodies 
melt  to  a  colourlefs  tranfparent  glafs  with  the  borax  ; 
for  inftance,  the  calcareous  fubftances  when  pure,  the 
fluors,  fome  of  the  zeolites,  &c.  Others  tinge  the  bo 
rax  with  a  green  tranfparent  colour,  viz.  the;  granules, 

C  trapp, 


C     «4     ] 

trapp,  fome  of  the  argillaceas,  andfome  of  die  micaceas 
and  afbeftinse.  This  green  has  its  origin  partly  from 
a  fmall  portion  of  iron  which  the  granates  particularly 
contain,  and  partly  from  phlogifton. 

Borax  can  only  diffolve  a  certain  quantity  of  the 
mineral  body  proportional  to  its  own.  Of  the  calca 
reous  kind  it  diflblves  a  vaft  quantity ;  but  turns  at 
laft,  when  too  much  has  been  added,  from  a  clear 
tranfparent  to  a  white  opaque  flag.  When  the  quan 
tity  of  the  calcareous  matter  exceeds  but  little  in  pro 
portion,  the  glafs  looks  very  clear  as  long  as  it  remains 
hot :  but  as  foon  as  it  begins  to  cool,  a  white  half 
opaque  cloud  is  feen  to  arife  from  the  bottom,  which 
fpreads  over  the  third,  half,  or  more  of  the  glafs  globe, 
in  proportion  to  the  quantity  of  calcareous  matter  ; 
but  the  glafs  or  flag  is  neverthelefs  fliining,  and  of  a 
glaffy  texture  when  broken.  If  more  of  this  matter  be 
added,  the  cloud  rifes  quicker  and  is  more  opaque, 
and  fo  by  degrees  till  the  flag  becomes  quite  milk 
white.  It  is  then  no  more  of  a  fhining,  but  rather 
dry  appearance,  on  the  furface  ;  is  very  brittle,  and 
of  a  grained  texture  when  broken. 

SECT.  II.  Of  Experiments  upon  Mdals  and  Ores. 
WHAT  has  been  hitherto  faid  relates  only  to  the 
Jtones  and  earths  :  We  fhall  now  proceed  to  defcribe  the 
manner  of  examining  metals  and  ores.  An  exaft  know 
ledge  and  nicety  of  procedure  are  fo  much  the  more 
neceilary  here,  as  the  metals  are  often  fo  difguifed  in 
their  ores,  as  to  be  very  difficultly  known  by  their  ex 
ternal  appearance,  and  liable  fometimes  to  be  miftaken 
one  .for  the  other :  Some  of  the  cobalt  ores,  for  in- 
ftance,  reiemble  much  the  pyrites  arfenicaus  ;  there  are 
alfo  fome  iron  and  lead  ores,  which  are  nearly  like 
one  another,  &c. 

As  the  ores  generally  confift  of  metals  mineralifed 
with  fulphur  or  arfenic,  or  fometimes  both  together, 
they  ought  firft  to  be  expofed  to  the  fire  by  them- 

felves, 


C    15    ] 

felves,  in  order  not  only  to  determine  with  which  of 
thefe  they  are  mineralifed,  but  alfo  to  fet  them  free 
from  thole  volatile  mineralifing  bodies  :  This  ferves 
inftead  of  calcination,  by  which  they  are  prepared  for 
further  allays. 

Here  it  mud  be  repeated,  that  whenever  any  me 
tal  or  fuiible  ore  is  to  be  tried,  a  little  concavity  mud 
be  made  in  that  place  of  the  charcoal  where  the  mat 
ter  is  to  be  put  ;  becaufe,  as  foon  as  it  is  melted,  it 
forms  itfelf  into  a  globular  figure,  and  might  then  roll 
from  the  charcoal,  if  its  furface  was  plain  ;  but  when 
borax  is  put  to  it,  this  inconvenience  is  not  fo  much 
to  be  feared. 

Whenever  an  ore  is  to  be  tried,  a  fmall  bit  beinsj 
broke  off  for  the  purpofe,  it  is  laid  upon  the  charcoal, 
and  the  flame  blown  on  it  flowly.  Then  the  fulphur 
or  arfenic  begins  to  part  from  it  in  form  of  fmoke  : 
thefe  are  eafily  diftinguilhed  from  one  another  by  their 
fmell ;  that  of  fulphur  being  fufficiently  known,  and 
the  arfenic  Ixnelling  like  garlick.  The  flame  ought 
to  be  blown  very  gently  as  long  as  any  fmoke  is  feen 
to  part  from  the  ore  ;  but  after  that,  the  heat  mutl 
be  augmented  by  degrees,  in  order  to  make  the  cal 
cination  as  perfecl:  as  poflible.  If  the  heat  be  applied 
very  ftrongly  from  the  beginning  upon  an  ore  that 
contains  much  fulphur  or  arfenic,  the  ore  will  prefent- 
ly  melt,  and  yet  lofe  very  little  of  its  mineralifing 
bodies,  by  that  means  rendering  the  calcination  very 
imperfect.  It  is,  however,  impoffible  to  calcine  the 
ores  in  this  manner  to  the  utmoft  perfection,  which  is 
eafily  feen  in  the  following  inftance,  viz.  in  melting 
down  a  calcined  potter's  ore  with  borax,  it  will  be 
found  to  bubble  upon  the  coal,  which  depends  on  the 
fulphur  which  is  ftill  left,  the  vitriolic  acid  of  this 
uniting  with  the  borax,  and  caufing  this  motion.  How 
ever,  lead  in  its  metallic  form,  melted  in  this  manner, 
bubbles  upon  the  charcoal,  if  any  fulphur  remains  in 
it.  But  as  the  lead  as  well  as  fome  of  the  other  metals, 
C  2  may 


[     16     ] 

may  raife  bubbles  upon  the  charcoal,  although  they 
are  quite  free  from  the  fulphur,  only  by  the  flames 
being  forced  too  violently  on  it,  thefe  phenomena 
ought  not  to  be  confounded  with  each  other. 

The  ores  being  thus  calcined,  the  metals  contained 
in  them  may  be  difcovered,  either  by  being  melted 
alone  or  with  fluxes ;  when  they  fhow  themfelves  ei 
ther  in  their  pure  metallic  ftate,  or  by  tinging  the  flag 
with  a  colour  peculiar  to  each  of  them.  In  thefe  expe 
riments  it  is  not  to  be  expected  that  the  quantity  of 
metal  contained  in  the  ore  fhould  be  exactly  deter 
mined  ;  this  mud  be  done  in  larger  laboratories.  This 
cannot,  however,  be  looked  upon  as  any  defect,  fmce 
it  is  fufficient  for  a  mineralogift  cnly  to  find  out  what 
fort  of  metal  is  contained  in  the  ore.  There  is  an 
other  circumftar-ce,  which  is  a  more  real  defect  in  the 
miniature  laboratories,  which  is,  that  fome  ores  are  not 
at  all. capable  of  oeing  tried  by  fo  fmall  an  apparatus  ; 
for  inftance,  tne  gold  ore  called  pyrites  aureus,  which 
confiiis  of  gold,  iron,  and  fulphur.  The  greateft  quan 
tity  of  gold  which  this  ore  contains  is  about  one 
ounce,  or  one  ounce  and  an  half,  out  of  100  pounds 
of  the  ore,  the  reft  being  iron  and  fulphur :  and  as 
only  a  very  fmall  bit  is  allowed  for  thefe  experiments, 
the  gold  contained  therein  can  hardly  be  difcerned  by. 
the  eye,  even  if  it  could  be  extrafted  ;  but  it  goes 
along  with  the  iron  in  the  flag,  this  laft  metal  being 
in  fo  large  a  quantity  in  proportion  to  the  other,  and 
both  of  them  having  an  attraction  for  each  other. 

The  blendes  and  black-jacks,  which  are  mineral 
zinc  ores,  containing  zinc,  fulphur,  and  iron,  cannot 
be  tried  this  way,  becaufe  they  cannot  be  perfectly 
calcined,  and  befides  the  zinc  flies  off  when  the  iron 
fcorifies.  Neither  can  thofe  blendes,  which  contain 
filver  or  gold  mineralifed  with  them,  be  tried  in  this 
manner,  which  is  particularly  owing  to  the  imperfect 
calcination.  Nor  are  the  quickfilver  ores  fit  for  thefe 
experiments :  the  volatility  of  that  femimetal  mak 
ing 


[     17     ] 

ing  it  impoflible  to  bring  it  out  of  the  poorer  fort 
of  ores  :  and  the  rich  ores,  which  fweat  out  the  quick* 
filver  when  kept  clofe  in  the  hand,  not  wanting  any 
of  thefe  allays,  £c.  Thefe  ores  ought  to  be  affayed 
in  larger  quantities,  and  even  with  fuch  other  methods 
as  cannot  be  applied  upon  a  piece  of  charcoal. 

Some  of  the  rich  filver  ores  are  eafily  tried  :  for  in- 
ftance,  minera  argentl  "u/Yra?,  cemmonly  called  Jilyer- 
glafs,  which  confiits  only  of  filver  and  fulphur.  When 
this  ore  is  expofed  to  the  flame,  it  melts  inftantly,  and 
the  fulphur  goes  away  in  fume,  leaving  the  filver  pure 
upon  the  charcoal  in  a  globular  form.  If  this  filver 
fliould  happen  to  be  of  a  dirty  appearance,  which  often 
is  the  cafe,  then  it  muft  be  melted  anew  with  a  very 
little  borax  ;  and  after  it  has  been  kept  in  fufion  for  a 
minute  or  two,  fo  as  to  be  perfectly  melted  and  red- 
hot,  the  proof  is  fuffered  to  cool :  it  may  then  be 
taken  off  the  coal ;  and  being  laid  upon  the  fteel- 
plate,  the  filver  is  feparated  from  the  flag  by  one  or 
two  ftrokes  of  the  hammer.  Here  the  ufe  of  the  brafs 
ring  is  manifeft  ;  for  this  ought  firft  to  be  placed  up 
on  the  plate,  to  hinder  the  proof  from  flying  offby  the 
violence  of  the  ftroke,  which  otherwife  would  happen. 
The  filver  is  then  found  inclofed  in  the  flag  of  a  glo 
bular  form,  and  quite  fliining,  as  if  it  was  polifhed. 
When  a  large  quantity  of  filver  is  contained  in  a  lead 
ore,  viz.  in  a  potter's  ore,  it  can  likewife  be  difcove- 
red  through  the  ufe  of  the  blow-pipe,  of  which  more 
will  be  mentioned  hereafter. 

Tin  may  be  melted  out  of  the  pure  tin  ores  in  its 
metallic  ftate.  Some  of  thefe  ores  melt  very  eafily, 
and  yield  their  metal  in  quantity,  if  only  expofed  to 
the  fire  by  themfelves  :  but  others  are  more  refractory- ; 
and  as  thefe  melt  very  flowly,  the  tin,  which  fvveats 
out  in  form  of  very  fmall  globules,  is  inftantly  burnt 
to  afhes  before  thefe  globules  have  time  to  unite  in 
order  to  compofe  a  larger  globe,  which,  might  be  feen 
C  3  by 


[     iS     ] 

by  the  eye,  and  not  fo  foon  deftroyed  by  the  fire  ;  it  is 
therefore  neceffary  to  add  a  little  borax  to  thefe  from 
the  beginning,  and  then  to  blow  the  flame  violently  at 
the  proof.  The  borax  does  here  preferve  the  metal 
from  being  too  foon  calcined,  and  even  contributes  to 
the  readier  collecting  of  the  fmall  metalic  particles, 
which  foon  are  feen  to  form  themfelves  into  a  globule 
of  metallic  tin  at  the  bottom  of  the  whole  mafs,  near- 
erh  to  the  charcoal.  As  foon  as  fo  much  of  the  me 
tallic  tin  is  produced  as  is  fufficient  to  convince  the 
operator  of  its  prefence,  the  fire  ought  to  be  difcon- 
tinued,  though  the  whole  of  the  ore  be  not  yet  melt 
ed  ;  becaufe  the  whole  of  this  kind  of  ore  can  be  fel- 
dom  or  never  reduced  into  metal  by  means  of  thefe 
experiments,  a  great  proportion  being  always  calcined  : 
and  if  the  fire  is  continued  too  long,  perhaps  even  the 
metal  already  reduced  may  likewife  be  burnt  to  afhes  ; 
for  the  tin  is  very  foon  deprived  of  its  metallic  (late  by 
the  fire. 

Moft  part  of  the  lead  ores  may  be  reduced  to  a 
metallic  (late  upon  the  charcoal.  The  minera  pluml'i 
calciformeS)  which  are  pure,  are  eafily  melted  into  lead  ; 
but  fuch  of  them  as  are  mixed  with  an  ochrafcrri,  or 
any  kind  of  earth,  as  clay,  lime,  &c.  yield  very  little 
of  lead,  and  even  nothing  at  all,  if  the  heterogenea  are 
combined  in  any  large  quantity  :  this  happens  even 
with  the  minera  pluml'i  calciformis  arfernco  mlxia.  Thefe 
therefore  are  not  to  be  tried  but  in  larger  laboratories. 
However,  every  mineral  body  fufpecled  to  contain- 
any  metallic  fubftance  may  be  tried  by  the  blow-pipe, 
fo  as  to  give  fufficient  proofs  whether  it  contain  any 
or  not,  by  its  effecls  being  different  from  thofe  of  the 
ftones  or  earths,  &c. 

The  mlncra  plumb't  miner  alt  fata  leave  the  lead  in  a 
metallic  form,  if  not  too  large  a  quantity  of  iron  is 
mixed  with  it.  For  example,  when  a  teflellated  or 
fteel-grained  lead  ore  is  expofed  to  the  flame,  its  ful- 

phur, 


C     '9     ] 

phur,  and  even  the  arfenic  if  there  be  any,  begins  to 
fume,  and  the  ore  itfelf  immediately  to  melt  into  a 
globular  form ;  the  reft  of  the  fulphur  continues  then 
to  fly  off,  if  the  flame  be  blown  flowly  upon  the  mafs  ; 
but,  on  the  contrary,  very  little  of  the  fulphur  will  go 
off,  if  the  flame  be  forced  violently  on  it :  in  this  cafe, 
it  rather  happens  that  the  lead  itfelf  crackles  and  difli- 
pates,  throwing  about  very  minute  metallic  particles. 
The  fulphur  being  driven  out  as  much  as  poflible, 
which  is  known  by  finding  no  fulphureous  vapour  in 
fmelling  at  the  proof,  the  whole  is  fuffered  to  cool, 
and  then  a  globule  of  metallic  lead  will  be  left  upon 
the  coal.  If  any  iron  is  contained  in  the  lead-ore, 
the  lead,  which  is  melted  out  of  it,  is  not  of  a  metal 
lic  {Lining,  but  rather  of  a  black  and  uneven,  furface : 
a  little  borax  muft  in  this  cafe  be  melted  with  it,  and 
as  foon  as  no  bubble  is  feen  to  rife  any  longer  from 
the  metal  into  the  borax,  the  fire  muft  be  difcontinued  : 
when  the  mafs  is  grown  cold,  the  iron  will  be  found 
fcorified  with  the  borax,  and  the  lead  left  pure  and  of 
a  fhining  colour. 

Borax  does  not  fcorify  the  lead  in  thefe  fmall  expe 
riments  when  it  is  pure  :  if  the  flame  is  forced  with  a 
violence  on  it,  a  bubbling  will  enfue,  refembling  that 
which  is  obferved  when  borax  diflblves  a  body  melted 
with  it ;  but  when  the  fire  ceafes,  *the  flag  will  be 
perfectly  clear  and  tranfparent,  and  a  quantity  of  very 
minute  particles  of  lead  will  be  feen  fpread  about  the 
borax,  which  have  been  torn  off  from  the  mafs  during 
the  bubbling. 

If  fuch  a  lead  ore  is  rich  in  filver,  this  laft  metal 
may  likewife  be  difcovered  by  this  experiment ;  becaufe 
as  the  lead  is  volatile,  ir  may  be  forced  off,  and  the 
filver  remain.  To  effect  this,  the  lead,  which  is  melt 
ed  out  of  the  ore,  muft  be  kept  in  conftant  fufion  with 
a  flow  heat,  that  it  may  be  confumed.  This  end  will 
be  fooner  obtained,  and  the  lead  part  quicker,  if  du 
ring  the  fufioa  the  wind  through  the  blow-pipe  ba 

directed 


[       20      ] 

directed  Immediately,  though  not  forcibly,  upon  the 
melted  mafs  itfelf,  until  it  begin  to  cool;  at  which 
time  the  fire  muft  be  directed  on  it  again.  The  lead, 
which  is  already  in  a  volatilifmg  ftate,  will  by  this  ar 
tifice  be  driven  out  in  form  of  a  fubtil  fmoke  ;  and  by 
thus  continuing  by  turns  to  melt  the  mafs,  and  then 
to  blow  off  the  lead,  as  has  been  faid,  until  no  fmoke 
is  any  longer  perceived,  the  filver  will  at  laft  be  ob 
tained  pure.  The  fame  obfervation  holds  good  here 
alfo,  which  was  made  about  the  gold,  that,  as  none 
but  very  little  bits  of  ores  can  be  employed  in  thefe 
experiments,  it  will  be  difficult  to  extract  the  filver 
out  of  a  poor  ore  :  for  fome  part  of  it  will  fly  off  with 
the  lead,  and  what  might  be  left  is  too  fmall  to  be  dif- 
cerned  by  the  eye.  The  filver,  which  by  this  means 
is  obtained,  is  eafily  diftinguiihed  from  lead  by  the 
following  external  marks,  viz.  that  it  muft  be  red-hot 
before  it  can  be  melted  :  it  cools  fooner  than  lead : 
it  has  a  filver  colour ;  that  is  to  fay,  brighter  and  whi 
ter  than  lead  :  and  is  harder  under  the  hammer. 

The  miners  cupri  calciformes  (at  lead  fome  of  them), 
when  not  mixed  with  too  much  ftone  or  earth,  are  ea- 
fily  reduced  to  copper  with  any  flux  ;  if  the  copper  is 
found  not  to  have  its  natural  bright  colour,  it  muft  be 
melted  with  a  little  borax,  which  purifies  it.  Some  of 
thefe  ores  do  not  all  difcover  their  metal  if  not  imme 
diately  melted  with  borax  ;  the  heterogenea  contained 
in  them  hindering  the  fufion  before  thefe  are  fcorified 
by  the  flux. 

The  grey  copper  ores,  which  only  confift  of  copper 
and  fulphur,  are  tried  almoft  in  the  fame  manner  as 
abovementioned.  Being  expofed  to  the  flame  by 
themfelves,  they  will  be  found  inftantly  to  melt,  and 
part  of  their  fulphur  to  go  off.  The  copper  may  af 
terwards  be  obtained  in  two  ways  :  the  one,  by  keep 
ing  the  proof  in  fufion  for  about  a  minute,  and  after 
wards  fuffering  it  to  cool;  when  it  will  be  found  to 
have  a  dark  and  uneven  appearance'  externally,  but 

which 


C     «     ] 

which  after  being  broken  difcovers  the  metallic  copper 
of  a  globular  form  in  its  centre,  furrounded  with  a  re- 
gulus,  which  ftill  contains  fome  fulphur  and  a  portion 
of  the  metal:  the  other,  by  being  melted  with  borax, 
which  laft  way  fometimes  makes  the  metal  appear 
fooner. 

The  miners  cupri  pyritacex,  containing  copper,  ful 
phur,  andiron,  may  be  tried  with  the  blow-pipe  if 
they  are  not  too  poor.  In  thefe  experiments  the  ore 
ought  to  be  calcined,  and  after  that  the  irofa  fcorified. 
For  this  purpofe  a  bit  of  the  ore  muft  be  expofed  to 
a  flow  flame,  that  as  much  of  the  fulphur  as  poffible 
may  part  from  it  before  it  is  melted,  becaufe  the  ore 
commonly  melts  very  foon,  and  then  the  fulphur  is 
more  difficultly  driven  off.  After  being  melted,  it 
mull  be  kept  in  fufion  with  a  ftrong  fire  for  about  a 
minute,  that  a  great  part,  of  the  iron  may  be  calcined  ; 
and  after  that,  fome  borax  mud  be  added,  which  fco- 
rifies  the  iron,  and  turns  with  it  to  a  black  flag.  If 
the  ore  is  very  rich,  metallic  copper  will  be  had  in  the 
flag  after  the  fcorifioation.  If  the  ore  be  of  a  moderate 
richnefs,  the  copper  will  ftill  retain  a  little  fulphur, 
and  fometimes  iron:  the  product  will  therefore  be 
brittle,  and  muft  with  great  caution  be  feparated  from 
the  flag,  that  it  may  not  break  into  pieces  ;  and  if 
this  producl  is  afterwards  treated  in  the  fame  manner 
as  before  faid,  in  fpeaking  of  the  grey  copper-ores, 
the  metal  will  foon  be  produced.  But  if  the  ore  is 
poor,  the  producl:  after  the  firft  fcorification  muft  be 
brought  into  fufion,  and  afterwards  melted  with  fome 
frefh  borax,  in  order  to  calcine  and  fcorify  the  remain 
ing  portion  of  iron ;  after  which  it  may  be  treated  as 
mentioned  in  the  preceding  paragraph.  The  copper 
will  in  this  laft  cafe  be  found  in  a  very  fmall  globule. 

The  copper  is  not  very  e'afily  fcorified  with  this  ap 
paratus,  when  it  is  melted  together  with  borax,  unlefs 
it  has  firft  been  expofed  to  the  fire  by  itfelf  for  a  while 
in  order  to  be  calcined.  When  only  a  little  of  this 

metal 


C       2*       ] 

metal  is  diffolved,  it  inftantly  tinges  the  flag  of  a  red- 
difli  brown  colour,  and  moRly  opaque  ;  but  as  foon  as 
this  flag  is  kept  in  fuiion  for  a  little  while,  it  becomes 
quite  green  and  tranfparent :  and  thus  the  prefence  of 
the  copper  may  be  difccvcred  by  tlyj  colour,  when  it 
is  concealed  in  heterogeneous  bodies,  fo  as  not  to  be 
difcovered  by  any  other  experiment. 

If  metallic  copper  is  melted  with  borax  by  a  flow 
fire,  and  only  for  a  very  little  time,  the  glafs  or  flag 
becomes  of  a  fine  tranfparent  blue  or  violet  colour,  in 
clining  more  or  lefs  to  the  green  :  but  this  colour  is 
not  properly  owing  to  the  copper,  but  it  may  rather 
be  to  its  phlogifton  ;  becaufe  the  fame  colour  is  to  be 
had  in  the  fame  manner  from  iron  ;  and  thefe  glaffes, 
which  are  coloured  with  either  of  thofe  two  metals, 
foon  lofe  their  colour  if  expofed  to  a  ftrong  fire,  in 
which  they  become  quite  clear  and  colourlefs.  Be- 
fides,  if  this  glafs,  tinged  blue  with  the  copper,  is  again 
melted  with  more  of  this  metal,  it  becomes  of  a  good 
green  colour,  which  for  a  long  time  keeps  unchanged 
in  the  fire. 

The  iron  ores,  when  pure,  can  never  be  melted 
per  fe,  by  the  means  of  the  blow-pipe  alone;  nor 
do  they  yield  their  rnetal  when  melted  with  fluxes  ; 
becaufe  they  require  too  ftrong  a  heat  to  be  brought 
into  fufion  ;  and  as  both  the  ore  and  the  metal  itfelf 
very  foon  lofe  their  phlogifton  in  the  fire,  and  cannot 
be  fupplied  with  a  fufficient  quantity  from  the  char 
coal,  fo  likewife  they  are  very  foon  calcined  in  the  fire. 
This  eafy  calcination  is  alfo  the  reafon  why  the  fluxes, 
for  inftance  borax,  readily  fcorify  this  ore,  and  even 
the  metal  itfelf.  The  iron  lofes  its  phlogifton  in  the 
fire  fooner  than  the  copper,  and  is  therefore  more  ea- 
fily  fcorified. 

The  iron  is,  however,  difcovered  without  much  dif 
ficulty,  although  it  were  mixed  but  in  a  very  fmall 
quantity  with  heterogeneous  bodies.  The  ore,  or 
thofe  bodies  which  contain  any  large  quantity  of  the 

metal, 


metal,  are  all  attra&ed  by  the  loadftone,  fome  without: 
any  previous  calcination,  and  others  without  having 
being  roafted.  When  a  clay  is  mixed  with  a  little 
iron,  it  commonly  melts  by  itfelf  in  the  fire ;  but  if 
this  metal  is  contained  in  a  limeftone;  it  does  not  pro 
mote  the  fufion,  but  gives  the  ft  one  a  dark  and  fome- 
times  a  deep  black  colour,  which  always  is  the  charac 
ter  of  iron.  A  minerafern  calcifornus  pura  cr^flallifata^ 
is  commonly  of  a  red  colour  :  This  being  expofed  to 
the  flame,  becomes  quite  black  ;  and  is  then  readily 
attracted  by  the  loadftone,  which  it  was  not  before. 
Eefides  thefe  figns,  the  iron  difcovers  itfelf,  by  tinging 
the  flag  of  a  green  tranfparent  colour,  inclining  to 
brown,  when  only  a  little  ot  the  metal  is  fcorified  ;  but 
as  foon  as  any  larger  quantity  thereof  is  dillblved  in 
the  flag,  this  becomes  firft  a  blackifli  brown,  and  after 
wards  quite  black  and  opaque. 

Bifmuth  is  known  by  its  communicating  a  yellow- 
ifh  brown  colour  to  borax ;  and  arfenic  by  its  volatili 
ty  and  garlick  fmell.  Antimony,  both  in  form  of  re- 
gulus  and  ore,  is  wholly  volatile  in  the  fire  when  it  is 
not  mixed  with  any  other  metal  except  arfenic  ;  and  is 
known  by  its  particular  fmell,  eafier  to  be  diftmguifh- 
ed  when  once  known  than  defcribed.  When  the  ore 
of  antimony  is  melted  upon  the  charcoal,  it  bubbles 
conftantly  during  its  volatilifmg. 

Zinc  ores  are  not  eafily  'tried  upon  the  coal ;  but 
the  regulus  of  zinc  expofed  to  the  fire  upon  the  char 
coal  burns  with  a  beautiful  blue  flame,  and  forms  it 
felf  almoft  inftantly  into  white  flowers,  which  are  the 
common  flowers  of  zinc. 

Cobalt  is  particularly  remarkable  for  giving  to  the 
glafs  a  blue  colour,  which  is  the  zaffre  or  frnalt.  To 
produce  this,  a  piece  of  cobalt  ore  muft  be  calcined 
in  the  fire,  and  afterwards  melted  with  borax.  As 
foon  as  the  gbfs,  during  the  fufion,  from  being  clear, 
feems  to  grow  opaque,  it  is  a  fign  that  it  is  already 
tinged  a  little  j  the  fire  is  thsn  to  be  difcontinued,  and 

the 


C   24   ] 

the  operator  mud  take  hold,  with  the  nippers,  of  a  little 
of  the  glafs,  whilft  yet  hot,  and  draw  it  out  flowly 
in  the  beginning,  but  afterwards  very  quick,  before 
it  cools,  whereby  a  thread  of  the  coloured  glafs  is 
procured,  more  or  lefs  thick,  wherein  the  colour  may 
eafier  be  feen  than  in  a  globular  form.  This  thread 
melts  eafily,  if  only  put  in  the  flame  ol  the  candle  with 
out  the  help  of  the  blow-pipe. — If  this  glafs  be  melted 
again  with  more  of  the  cobalt,  and  kept  in  fufion 
for  a  while,  the  colour  becomes  very  deep  ;  and  thus 
the  colour  may  be  altered  at  pleafure. 

When  the  cobalt  ore  is  pure,  or  at  lead  contains 
but  little  iron,  a  cobalt  regulus  is  almoft  inftantly 
produced  in  the  borax  during  the  fufion  ;  but  when 
it  is  mixed  with  a  quantity  of  iron,  this  lafl  metal 
ought  firft  to  be  feparated,  which  is  eafily  performed 
fmce  it  fcorifies  fooner  than  the  cobalt ;  therefore,  as 
long  as  the  flag  retains  any  brown  or  black  colour,  it 
muft  be  feparated,  and  melted  again  with  frefli  borax, 
until  it  fliows  the  blue  colour. 

Nickel  is  very  feldom  to  be  had ;  and  as  its  ores  are 
feldom  free  from  mixtures  of  other  metals,  it  is  very 
difficultly  tried  with  the  blow-pipe.  However,  when 
this  femimetal  is  mixed  with  iron  and  cobalt,  it  is 
eafily  freed  from  thefe  heterogeneous  metals,  and  re 
duced  to  a  "pure  nickel  regulus  by  means  cf  fcorificati- 
on  with  borax,  becaufe  both  the  iron  and  cobalt  fooner 
fcorify  than  the  nickel.  The  regulus  of  nickel  itfelf  is 
of  a  green  colour  when  calcined  :  it  requires  a  pretty 
ftrong  fire  before  it  melts,  and  tinges  the  borax  with  a 
hyacinth  colour.  Manganefs  gives  the  fame  colour  to 
borax ;  but  its  other  qualities  are  quite  different,  fo  as 
not  to  be  confounded  with  the  nickel. 

BY  means  of  the  foregoing  explanations,  and  thofe 
given  under  the  article  Bu>w-Pipe,  any  gentleman, 
who  is  a  lover  of  this  fcience,  will  be  able,  in  an  eafy 
manner,  to  amufe  himfelf  in  difcovering  the  properties 

of 


C    25    ] 

ef  thofe  works  of  nature,  with  which  the  mineral 
kingdom  furnilhes  us  ;  or  more  ufefully  to  employ 
himielf  by  finding  out  what  forts  of  ftones,  earths, 
ores,  &c.  there  are  on  his  eftate,  and  to  what  econo 
mical  purpofes  they  may  be  employed.  The  fcienti- 
fic  mineralift  may,  by  examining  into  the  properties 
and  effects  of  the  mineral  bodies,  dilcover  the  natural 
relation  thefe  bodies  ftand  in  to  each  other,  and  there 
by  furnifti  himfelf  with  materials  for  eftabliihing  a  mi 
neral  fyftem,  founded  on  fuch  principles  as  Nature  her- 
felf  has  laid  down  in  them  ;  and  this  in  his  own  (ludy, 
without  being  forced  to  have  recourfe  to  great  laborato 
ries,  crucibles,  furnaces,  &c.  which  is  attended  with 
much  trouble,  and  is  the  reafon  why  fo  few  can  have  an 
opportunity  of  gratifying  their  defire  of  knowledge  in 
this  part  of  natural  hiftory.  Farther  improvements 
of  this  apparatus  may  ftill  be  made  by  thofe  who 
choofe  to  beftow  their  attention  upon  it. 

A  great  number  of  fluxes  might,  perhaps,  be 
found  out,  whofe  effects  might  be  different  from, 
thofe  already  in  ufe,  whereby  more  diftincl  cha 
racters  of  thofe  mineral  bodies  might  be  difcover- 
ed,  which  now  either  fhow  ambiguous  ones,  or  which 
it  is  almoft  impoffible  to  try  exactly  with  the  blow 
pipe.  Inftead  of  the  Jal  fod&,  fome  other  fait  might 
be  difcovered  better  adapted  to  thefe  experiments. 
But  it  is  very  neceffary  not  to  make  ufe  of  any  other 
fluxes  on  the  charcoal  than  fuch  as  have  no  attrac 
tion  to  it:  if  they,  at  the  fame  time,  be  clear  and 
tranfparent,  when  melted,  as  the  borax  and  the  fal 
fiijibile  mlcrocofmicum,  it  is  ftill  better  :  however,  the 
tranfparency  and  opacity  are  of  no  great  confequence, 
if  a  fubftance  be  affayed  only  in  order  to  difcover  its 
fufibility,  without  any  attention  to  its  colour ;  ia 
which  cafe,  fome  metallic  flag,  perhaps,  might  be  ufe- 
ful. 

When  fuch  ores  are  to  be  reduced  whofe  metals 

-are  very  eaiily  calcined.,  as  tin,  zinc,  &c.  it  might 

1)  perhaps 


-  C    26    ] 

perhaps  be  of  fervice  to  add  fome  phlogiftic  body, 
iuch  as  hard  refm,  fmce  the  charcoal  cannot  afford 
enough  of  it  in  the  open  fire  of  thefe  afiays.  The 
manner  of  melting  the  volatile  metals  out  of  their 
oies  per  defcenfum  might  alfo,  perhaps,  be  imitated  : 
for  inftance,  a  hole  might  be  made  in  the  charcoal, 
wide  above  and  very  narrow  at  the  bottom  ;  a  little 
piece  of  the  ore  being  then  laid  at  the  upper  end 
of  the  hole,  and  covered  with  fome  very  fmall  pieces 
of  the  charcoal,  the  flame  muft  be  directed  on  the  top  : 
the  metal  might,  perhaps,  by  this  method,  run  into  the 
hole  below,  concealed  from  the  violence  of  the  fire, 
particularly  if  the  ore  is  very  fufible,  &c. 

The  ufe  of  the  apparatus  above  referred  to,  and 
which  may  be  called  a  pocket  laboratory  (as  the  whole 
admits  of  being  eaiily  packed  into  a  fmall  cafe),  is 
chiefly  calculated  for  a  travelling  mineralift.  But  a 
perfon  who  always  refides  at  one  and  the  fame  place, 
may  by  fome  alteration  make  it  more  commodious 
to  himfelf,  and  avoid  the  trouble  of  blowing  with  the 
mouth.  For  this  purpofe  he  may  have  the  blow-pipe 
go  through  a  hole  in  a  table,  and  fixed  underneath 
to  a  fmall  pair  of  bellows  with  double  bottoms,  fuch 
sis  fome  of  the  glafs-blowers  ufe,  and  then  nothing 
more  is  required  than  to  move  the  bellows  with  the 
feet  during  the  experiment ;  but  in  this  cafe  a  lamp 
may  be  ufed  inftead  of  a  candle.  This  method  would 
be  attended  with  a  ftill  greater  advantage,  if  thsre 
were  many  fuch  parts  as  c,  fig.  13.  the  openings  of 
which  were  of  different  dimenfions  :  thofe  parts  might 
by  means  of  a  fcrew  be  fattened  to  the  main  body  of 
the  blow-pipe,  and  taken  away  at  pleafure.  The  ad 
vantage  of  having  thefe  nozzles  of  different  capacities 
at  their  ends,  would  be  that  of  exciting  a  ftronger 
or  weaker  heat  as  occafion  might  require.  It  would 
only  be  neceffary  to  obferve,  that  in  proportion  as  the 
opening  or  noz/.le  of  the  pipe  is  enlarged,  the  quan 
tity  of  the  flame  muft  be  augmented  bj  a  thicker 

wick 


wick  in  the  lamp,  and  the  force  of  blowing  encreafed 
by  means  of  weights  laid  on  the  bellows  ;  a  much  in- 
tenfer  heat  would  thus  be  produced  by  a  pipe  of  a 
considerable  opening  .at  the  end,  by  which  the  expe 
riments  muft  undoubtedly  be  carried  farther  than  the 
common  blow-pipe. 

A  traveller,  who  has  feldom  an  opportunity  of 
carrying  many  things  along  with  him,  may  very  well 
be  contented  with  this  laboratory  and  its  apparatus, 
which  are  fufficient  for  mod  part  of  fuch  experiments 
as  can  be  made  on  a  journey.  There  are,  however, 
other  things  very  ufeful  to  have  at  hand  on  a  journey, 
which  ought  to  make  a  feparate  part  of  a  portable  la 
boratory,  if  the  manner  of  travelling  does  not  oppofe 
it :  this  ccnfifts  of  a  little  box  including  the  different 
acids,  and  one  or  two  matrafles,  in  order  to  try  the 
mineral  bodies  in  liquid  menftrua  if  required. 

Thefe  acids  are,  the  acid  of  nitre,  of  vitriol,  and 
of  common  fait.  Moft  of  the  ftones  and  earths  are 
attacked,  at  leaft  in  fome  degree,  by  the  acids ;  but 
the  calcareous  are  the  eafieft  of  all  to  be  diiTolved  by 
them,  which  is  accounted  for  by  their  calcareous  pro 
perties.  The  acid  of  nitre  is  that  which  is  moft  ufed 
in  thefe  experiments ;  it  diffolves  the  limeftone,  when 
pure,  perfectly,  with  a  violent  effervefcence,  and  the 
iblution  becomes  clear  :  when  the  limeftone  enters  in 
to  fome  other  body,  it  is  neverthelefs  difcovered  by 
this  acid,  through  a  greater  or  lefs  effervefcence  in 
proportion  to  the  quantity  of  the  calcareous  particles, 
unlefs  there  are  fo  few  as  to  be  almoft  concealed  from 
the  acid  by  the  heterogeneous  ones.  In  this  manner 
a  calcareous  body,  which  fora-times  nearly  refembles 
a  fiiiceous  or  argillaceous  one,  may  be  known  from 
thsfe  latter,  without  the  help  of  the  blow-pipe,  only  by 
pouring  one  or  two  drops  of  this  acid  upon  the  fiuV 
jecl:  ;  which  is  very  convenient  when  there  is  no  oppor 
tunity  nor  time  of  ufmg  this  inftrument. 

D  3.  The: 


[     28     ] 

The  gypfa,  which  confift  of  lime  and  the  vitriolic 
acid,  are  not  in  the  leaft  attacked  by  the  acid  of 
nitre,  if  they  contain  a  fufficient  quantity  of  their  own 
acid  ;  becaufe  the  vitriolic  acid  has  a  ftronger  attrac 
tion,  to  the  lime  than  the  acid  of  nitre  :  but  if  the 
calcareous  fubflance  is  not  perfectly  faturated  with 
the  acid  of  vitriol,  then  an  effervefcence  arifes  with  the 
acid  of  nitre,  more  or  lefs  in  proportion  to  the  want  of 
the  vitriolic  acid.  Thefe  circumftances  are  often  very 
effential  in  diftinguifliing  the  calcarea  and  gypfa  from 
one  another. 

The  acid  of  nitre  is  likewife  necetfary  in  trying  the 
zeolites,  of  which  fome  fpecies  have  the  fmgular  ef 
fect  to  diilblve  with  efrervefcence  in  the  abovemention- 
ed  acid  ;  and  within  a  quarter  of  an  hour,  or  even 
fometimes  not  until  feveral  hours  after,  to  change  the 
whole  folution  into  a  clear  jelly,  of  fo  firm  a  confidence, 
that  the  glafs  wherein  it  is  contained  may  be  reversed 
without  its  falling  out. 

If  any  mineral  body  is  tried  in  this  menftruum,  and 
only  a  fmall  quantity  is  fufpected  to  be  difiblved, 
though  it  was  impoffible  to  diftinguifti  it  with  the  eye 
during  the  folution,  it  can  be  eafily  difcovered  by 
adding  to  it  ad  faiuntatem  a  clear  folution  of  the  al 
kali,  when  the  diiTolved  part  will  be  precipitated,  and 
fall  to  the  bottom.  For  this  purpofe  the  falfodce  may 
b  e  very  ufeful. 

The  acid  of  nitre  will  fuffice  for  making  experiments 
upon  ftones  and  earths  ;  but  if  the  experiments  are  to 
be  extended  to  the  metals,  the  other  two  acids  are  alfo 
necefTary. 

Another  inftrument  is  likewife  necefiary  to  a 
complete  Pocket  Laboratory,  viz.  a  waihing -trough 
(fig.  21.),  in  which  the  mineral  bodies,  and  particu 
larly  the  ores,  may  be  feparated  from  each  other,  and 
from  the  adherent  rock,  by  means  of  water.  This 
trough  is  very  common  in  laboratories,  and  is  ufed  of 
different  fizes  ;  but  here  only  one  is  required  of  a 

moderate 


t     *9    3 

moderate  fize,  fucli  as  12  inches  and  a  half  long,  three 
inches  broad  at  the  one  end  and  one  inch  and  a  half 
at  the  other  end,  floping  down  from  the  fides  and 
the  broad  end  to  the  bottom,  where  it  is  three  quar 
ters  of  an  inch  deep.  It  may,  however,  be  made  of 
much  fmaller  dimenfions.  It  is  commonly  made  of 
wood,  which  ought  to  be  chofen  fmooth,  hard,  and 
compact,  wherein  are  no  pores  in  which  the  minute 
grains  of  the  pounded  matter  may  conceal  themfelves. 
It  is  to  be  obferved,  that  if  any  fuch  matter  is  to  be 
wafhed  as  is  fufpected  to  contain  feme  native  metal, 
iuch  as  filver  or  gold,  a  trough  fhould  be  procured  for 
this  purpofe  of  a  very  ihallow  Mope  ;  becaufe  the  mi 
nute  particles  of  the  native  metal  have  then  more  pow 
er  to  affemble  together  at  the  broad  end,  and  feparate 
from  the  other  matter. 

The  management  of  this  trough,  or  the  manner  of 
wafhing*  eonfifts  in  this  :  That  when  the  matter  is 
mixed  with  about  three  or  four  times  its  quantity  of 
water  in  the  trough,  this  is  kept  very  loofe  between 
two  fingers  of  the  left  hand,  and  fome  light  ftrokes 
given  on  its  broad  end  with  the  right,  that  it  may 
move  backwards  and  forwards  ;  by  which  means  the 
heavieft  particles  affemble  at  the  broad  and  lower  end,, 
from  which  the  lighter  ones  are  to  be  feparated  by 
inclining  the  trough  and  pouring  a  little  water  on 
them.  By  repeating  this  prccefs,  all  fuch  particles 
as  are  of  the  fame  gravity  may  be  collected  together, 
and  feparated  from  thofe  of  different  gravity,  provided 
they  were  before  equally  pounded  :  though  fuch  as 
are  of  a  clayey  nature,  are  often  very  difficult  to  fe 
parate  from  the  reft,  which,  however,  is  of  no  great 
confequcnce  to  a  Ikilful  and  experienced  wafher.  The 
walliing  procefs  is  very  neceiTary,  as  there  are  often 
rich  ores,  and  even  native  metals,  found  concealed  in 
earths  and  fand  in  fuch  minute  particles  as  not  to  be 
difcovered  by  any  other  means. 

D  3  SECT.  III. 


E    30   3 

SECT.  III.    Defcription  of  an  Improved  Portable  Labora 
tory  for  a/faying  Minerals. 

THE  chief  pieces  and  implements  of  the  portable 
laboratories  are  reprefented  in  Plate  XCIX.  at  B Low- 
Pipe,  and  in  Plate  CCCXIII.  annexed  to  the  prefent 
article. 

I.  The  firft  contains  thofe  belonging  to  the  Dry  Labo 
ratory,  fo  called  on  account  of  its  containing  whatever 
is  required  to  try  all  kinds  of  foffils  in  the  dry  way  by 
fire,  without  any  of  the  humid  menftruums.  They 
are  made  to  pack  in  a  box  of  the  fize  of  an  octavo 
book,  lined  with  green  velvet,  and  covered  with  black 
fifh-fkin  ;  the  infide  divided  into  different  compart 
ments,  fuited  to  the  fize,  form,  and  number  of  the 
implements  it  is  to  contain.  Of  thefe  the  principal 
are  defcribed  under  BLOW- Pipe.  We  muft  here,  how 
ever,  add  the  following  remarks  and  alterations  of  that 
inftrument  by  Mr  Magellan. 

D  and  Q__  (fig,  13.)  are  the  two  pieces  that  form 
the  blow-pipe,  which  is  here  reprefented  entire.  This 
very  ufeful  inftrument  has  been  considerably  improved 
of  late  in  England.  The  mouth-piece  a  a  is  made  of 
ivory,  to  avoid  the  difagreeable  fenfation  of  having  a 
piece  of  metal  a  long  time  between  the  teeth  and  lips,, 
which,  if  not  of  filver  or  gold,  may  be  very  noxious 
to  the  operator  ;  a  circumitance  that  has  been  hardly 
noticed  before. 

i.  If  the  mouth-piece  a  a  be  made  of  a  round  form, 
it  cannot  be  held  for  any  length  of  time  between  the 
teeth  and  lips,  to  blow  through  it,  without  draining 
the  mufcles  of  the  mouth,  which  produces  a  painful 
fenfation.  It  muft,  therefore,  have  fuch  an  external 
figure,  as  to  adapt  itfe/f  accurately  to  the  lateral 
angles  of  the  lips,  having  a  flattifh  oval  form  external 
ly,  with  two  oppofite  corners  to  fit  thofe  internal  an-j 
gles  of  the  mouth,  when  it  is  held  between  the  lips,  as 
may  be  feen  in  that  reprefented  in  the  figure. 

2.  The_ 


C    3'     1 

2.  The  fmall  globe  Ib  is  hollow,  for  receiving  the 
moifture  of  the  breath  ;  and  muft  be  compofed  of  two 
hemiipheres,  exadtly  fcrewing  into  one  another  in  bb  ; 
the  male-fcrew.is  to  be  in  the  lower  part,  and  foldered 
on  the  crooked  part  Q^of  the  tube  Q_P>  at  fuch  a 
diftance,  that  the  infide  end  of  the  crooked  tube  be 
even  with  the  edge  of  the  hemifphere,  as  reprefented 
by  the  pointed  lines  in  the  figure.     But  the  upper  he 
mifphere  is  to  be  foldered  at  the  end  of  the  ftraight  tube 
D.     By  thefe   means,  the  moifture  arifmg  from  the 
breath  falls  into  the  hollow  of  the  lower  hemifphere, 
where  it  is  colle&ed  round  the  upper  infide  end  of  the 
crooked  part  Q^of  the  blow-pipe,  without  being  apt  to 
fall  into  it. 

3.  The  fmall  nozzles,  or  hollow  conical  tubes,  ad- 
vifed  by  MelTrs  Engeftrom,  Bergman,  and  others,  are 
wrong  in  the  principle  ;  becaufe  the  wind  that  palfes 
from  the  mouth  through  fuch  long  cones  lofes  its  ve 
locity  by  the  lateral  fridion,  as  happens  in  hydraulic 
fpouts  ;  which,  when  formed  in  this  manner,  do  never 
throw  the  fluid  fo  far  as  when  the  fluid  pafles  through 
a  hole  of  the  fame  diameter,  made  in  a  thin  plate  of  a 
little  metallic  cap  that  fcrews  at  the  end  of  the  large 
pipe.     It  is  on  this  account  that  the  little  cap  c  is  em 
ployed,  having  a  fmall  hole  in  the  thin  plate,  which 
ferves  as  a  cover  to  it ;  and  there  are  feveral  of  thefe 
little  caps,  with  holes  of  fmaller  and  larger  fizes,  to 
be  changed  and  applied  whenever  a  flame  is  required 
to  be  more  or  lefs  ftrong. 

4.  Another  convenience  of  thefe  little  caps  is,  that 
even  in  cafe  any  moifture  fhould  efcape  falling  into  the 
hemifphere  bb,  and  pafs  along  with  the  wind  through 
the  crooked  pipe  Q^,  it  never  can  arrive  at  nor  obftruct 
the  little  hole  ot  the  cap  c,  there  being  room  enough  un 
der  the  hole  in  the  infide,  where  this  moifture  muft  be 
flopped  till  it  is  cleaned  and  wiped  out. 

The  ftream  of  air  that  is  impelled  by  the  blow 
pipe  (as  feen  in  fig.  3.)  upon  the  flame,  muft  be  ccn- 

ftant 


ftant  and  even,  and  muft  laft  as  long  as  the  experi 
ment  continues  to  require  it.  This  labour  will  fatigue 
the  lungs,  unlefs  an  equable  and  uninterrupted  infpi- 
ration  can  at  the  fame  time  be  continued.  To  fucceed 
in  this  operation  without  inconvenience,  fome  labour 
and  practice  are  neceflary,  as  already  explained  under 
the  detached  article. 

Every  affay  ought  always  to  begin  by  the  exterior 
flame,  which  muft  be  firft  directed  upon  the  mafs  under 
examination  ;  and,  when  its  efficacy  is  well  known,  then 
the  interior  blue  flame  is  to  be  employed. 

After  the  ore  is  roafted,  it  is  to  be  rounded  up 
on  the  fteel  plate  by  the  hammer  ;  the  particles  being 
prevented  from  being  diflipated  by  the  ring  H  (fig.  9, 
Plate  XCIX.),  within  which  the  pieces  to  be  broken 
are  to  be  put. 

Among  the  apparatus,  befide  the  particulars  al 
ready  mentioned,  three  phials  are  necerTary,  contain 
ing  the  required  fluxes,  viz.  the  borax,  the  fal  fodte, 
and  fcl  fufil tie  microcofmicum.  Other  ufeful  particulars 
are,  A  fmall  link  of  hard  fteel,  to  try  the  hardnefs  or 
foftnefs  of  mineral  fubftances,  and  alfo  to  ftrike  fire 
for  lighting  the  candle  when  required  :  A  piece  of 
black  flint,  toferve  as  a  touch-ftone  ;  (for  being  rubbed 
with  any  metal,  if  it  be  gold  the  marks  will  not  be 
corroded  by  aqua  fortis)  ;  and  alfo  to  ftrike  fire,  when 
necerTary,  with  the  link  of  fteel :  An  artificial  load- 
ftone,  properly  armed  with  iron,  for  the  better  pre- 
fervation  of  its  attractive  power  ;  (it  ferves  to  difcover 
the  ferrugineous  particles  of  any  ore  after  it  has  been 
roafted  and  powdered:)  A  triple  magnifier,  which, 
differently  combined,  produces  feven  magnifying 
powers,  the  better  to  diftinguifh  the  ftructure  and  me 
tallic  parts  of  ores,  and  the  minute  particles  of  native 
gold,  whenever  they  contain  that  metal  :  A  file,  to  try 
the  hardnefs  of  ftones  and  cryftals,  &c. :  Some  pieces 
of  dry  agaric  or  tinder,  and  fmall  bits  or  fplinters  of 
wood  tipped  with  brimftone,  to  ferve  as  matches  for 

lighting 


C     33     3 

lighting  the  candle ;  and  various  other  little  articles  of 
ule  in  thefe  experiments. 

II.  For  performing  experiments  in  the  Humid  IVay, 
the  chief  additional  articles  (and  which  muft  be  kept 
in  a  feparate  cafe)  confift  of  a  collection  of  phials, 
containing  the  principal  acids,  tefts,  precipitants,  and 
re-agents,  both  for  examining  mineral  bodies  by  the 
humid  way,  and  for  analyiing  the  various  kinds  of  mi 
neral  waters.  Thofe  with  acids  and  corrofive  folutions 
have  not  only  ground  ftoples,  but  alfo  an  external  cap 
to  each,  ground  over  the  ftople,  and  fecured  down 
ward  by  a  bit  of  wax  between  both,  in  order  to  con 
fine  the  corrofive  and  volatile  fluids  within.  But  thofe 
which  contain  mild  fluid  liquors  have  not  fuch  external 
caps  :  and  thofe  with  dry  inoffenfive  fubftances  are 
only  flopped  with  cork.  Befides  thefe  phials,  there 
are  two  fmaller  cylindrical  ones,which  ferve  to  exhi 
bit  the  changes  of  colour  produced  by  fome  of  the  re 
agents  in  thofe  analytical  aflays.  There  are  alfo  two 
or  three  fmall  matrafles,  to  hold  the  fubftances  with 
their  folvents  over  the  fire;  a  fmall glafs  funnel,  for 
pouring  the  fluids  ;  a  fmall  porcelain  mortar,  with  its 
peftle  ;  one  or  two  crucibles  of  the  fame  fubftance ;  a 
imail  wooden  trough  to  wafti  the  ground  ores ;  fome 
glafs  flicks  to  flir  up  the  fluid  mixtures ;  and,  finally, 
pieces  of  paper  tinged  red,  yellow,  and  .blue,  by  the 
tinctures  of  Fernambuc  wood  (commonly  called  Brafil 
wood),  turmeric,  and  litmus,  thickened  with  a  little 
March. 

The  following  lift  contains  the  names  of  the  various 
fluid  tefts  and  re-agents  that  are  neceffary  for  thefe  af- 
fays.  But  the  whole  number  being  too  large  to  be  all 
contained  in  a  portable  cafe,  every  one  may  give  the 
preference  to  thofe  he  likes  beft. 
i.  Concentrated  vitriolic  2.  Nitrous  acid,  purified 

acid,      whofe      fpecific        by  the  nitrous  folution 

gravity  may  be  expref-        of  filver. 

fed  in  the  outfide. 

s.  Con- 


[     34     ] 

3-     Concentrated    marine   4.    Marine    acid    dephlo- 

acid,    with    its  fpecifk        giilicated. 

gravity. 
5.  Aqua   regia  for  gold,   6.  Aqua  regia  for  platina 

viz.   2  nit.   and   i   ma-       viz.    half    marine    and 

rine,  half  nitrous  acid. 

7.  Nitrous  folntion  of  fil-  8.  Nitrous  folution  of  mer- 

ver.  cury,  made  in  the  cold. 

9=     Muriatic    folution    of  10.    Nitrous    folution    of 

barytes.  lime. 

n.    Muriatic    folution  of  12.  Mercury  in  its  metal- 

lime.  lie  ftate. 

13.     Corrofive   fublimate   14.  White  arfenic. 

of  mercury. 
15.     Nitrous    folution   of  16.    Nitrous    folution    of 

filver.  copper. 

17.     Acid  of  fugar.  18.     Liquor    probatorius 

vim. 
19.  Hepar  fulphuris.  20.  Oil   of  tartar  per  dell- 


21.  Salt  of  tartar.  22.  Cauftic  vegetable  al 

kali. 

23,  Pearl-afhes.  24.    Soap-makers  ley. 

25.  Common  fait.  26.     Vitriolated      argilla 

(alum.) 
27    Vitriol  of  iron  (cop-   28.  Nitrous  folution  of  fil- 

peras)  ver. 

29.  Acetous    folution    of  30.     Acetous  folution  of 

lead.  barytes. 

31.  Phlogifticated     alkali  32.     Lime-Water. 

by  the  Pruflian  blue. 

33.  Lime-water  phlogifti-  34.  Cauftic  volatile  alkali. 
cated    by    the  Pruffian 
blue. 
35.    Mild    volatile    alkali  36.     Reclified    fpirit    (aU 

(dry.)  cohol. 

37.  uEther.  38.     Spirituous     tinclure 

of  galls. 

The 


C     35     ] 

The  following  tefts  are  very  fit  alfu  for  thefe  allays, 
viz.  39,  Spirituous  folutions  of  foap  ;  40*  Syrup  of 
violets;  41  Tincture  of  litmus;  42.  Tincture  of  Brafil 
wood  ;  43.  Tincture  of  turmeric  ;  44.  Oil  of  olives  ; 
45.  Oil  of  linfeed  :  46.  Oil  of  turpeatine  ;  47.  Effential 
fait  of  wild -for  rel ;  48.  Hepar  fulphuris  :  49.  Sugar  of 
lead  ;  50.  Solution  of  alum. 

The  method  of  applying  the  above  tefts  of  acids 
and  re-agents  may  be  feen  in  Bergman's  treatifes  of 
the  Analyfis  of  Waters,  and  of  Allaying  by  the  Hu 
mid  Way  ;  in  Kirwan's  Elements  of  Mineralogy  ;  in 
the  Elements  of  Chemiftry  of  Dijon  ;  in 'the  Memoirs 
of  the  fame  Academy  ;  in  Fourcroy's  Lectures  of  Che- 
mi  ftry,  &c. 

III.  The  Lamp-furnace  Laboratory,  for  experiments 
both  by  the  humid  a.\\&  the  dry  way,  is  a  very  curious  and 
uieful,  though  fmall  apparatus.  It  is  an  improvement 
of  that  which  was  contrived  by  M.  de  Morveau,  in 
confequence  of  the  information  he  received  from  his 
friend  the  prefident  de  Virly,  who  faw  at  Upfal  how 
advantageoufly  the  late  eminent  profeffor  Bergman 
availed  himfelf  of  this  convenience  for  many  analytical 
procefles  in  miniature,  by  the  ufe  of  very  fmall  giafs 
veffels  about  one  inch  diameter,  and  other  implements 
of  proportional  fixe,  for  performing  various  chemical 
operations.  (See  the  Dijon  Memoirs  for  1783.  Part  i» 
p.  171.) 

There  can  be  no  doubt  but  that  whenever  thefe 
proceiles  are  properly  conducted,  though  in  miniature, 
the  lamp-furnace  will  prove  amply  fufficient  to  per 
form  in  a  few  minutes,  and  with  very  little  expence, 
the  various  folutions,  digeftions,  and  diftillations, 
which  otherwife  would  require  large  vefTels,  (tills,  re 
torts,  reverberatory  furnaces,  £c.  to  afcertain  the  com 
ponent  parts  of  natural  bodies  ;  though  it  is  not  always 
fufficient  to  afcertain  their  refpective  quantities.  In 
this  laft  cafe,  operations  muft  be  performed  in  great 
laboratories,  and  on  a  large  fcule,  at  a  conflderable 

expence 


C    36    ] 

expence.  But  the  fubftances  are  fometimes  too  valu 
able  ;  as,  for  inflance,  when  precious  ftones  are  exami 
ned  ;  and  of  courfe  the  lafl  way  never  can  be  attemp 
ted  in  fuch  cafes. 

Thefe  fmall  procefles  have  likewife  another  advan* 
tage  before  noticed,  which  cannot  be  obtained  in 
works  at  large.  It  confifts  in  one's  being  able  to  ob- 
ferve  the  gradual  progrefs  of  each  operation  ;  of  eafily 
retarding  or  urging  it,  as  it  may  require  :  and  of  af- 
certaining  at  pleafure  each  ftep  of  every  experiment, 
together  with  the  phenomena  attending  the  fame. 

The  lamp-furnace  is  mounted  in  a  fmall  parallelo 
gram  of  mahogany,  about  fix  inches  long  and  four 
wide,  marked  fig.  5.  This  is  kept  fteady  over  the 
edge  of  a  common  table,  by  means  of  the  metallic 
clamp  auiu,  which  is  fattened  by  the  fcrew  x.  The 
pillar  rs  is  fcrewed  in  a  vertical  pofition  on  the  plate  s, 
being  about  ten  inches  high  :  the  other  is  fcrewed  to 
the  oppofite  corner,  marked/^,  and  is  only  7^  inches 
long ;  both  are  compofed  of  two  halves,  that  fcrew  at 
fly  to  be  eafily  packed  up  with  all  the  implements  in 
a  cafe  covered  with  black  fifh  fkin,  and  lined  with 
green  velvet,  like  the  other  laboratory  already  de- 
icribed. 

The  lamp  /£,  fig.  3.  is  fupported  on  the  plate  /, 
which  has  a  ring  /  that  runs  in  the  column  pk,  and 
may  be  fixed  by  its  fcrew  /  at  the  required  height.-— 
This  lamp  has  three  fmall  pipes  of  different  fizes,  to 
receive  as  many  wicks  of  different  thicknefs,  and  to 
be  filled  with  fpirit  of  wine.  By  a  fimilar  method > 
a  piece  of  charcoal  is  mounted  and  fupported  by  the 
pliers  or  little  forceps  fcrewed  to  the  arm  ac9  fig.  i. 
which  has  all  the  motions  requifite  for  being  fixed  by 
means  of  proper  fcrews,  at  a  proper  di fiance  from 
the  flame  of  the  wick  h.  The  blow-pipe,  fig.  4.  is, 
by  a  fimilar  mechanifm,  mounted  on  the  fmaller  co 
lumn  pq,  at  fuch  adiftanceasto  blow  the  flame/?*'  to 
the  piece  of  ore  m9  which  is  upon  the  charcoal  gf. 

4  Every 


[     37     ] 

Every  thing  being  difpofed  in  this  manner,  the  ope*, 
rator  blows  through  the  mouth-piece  of  the  blow 
pipe,  fig.  4.  and  remains  with  his  hands  free  to  make 
the  changes  and  alterations  he  may  think  proper. — 

£JV.  B.  The  large  round  cavity  e  in  the  middle  of  the 
parallelogram,  fig.  5.  is  to  receive  the  lamp  /•,  fig.  3* 
when  all  the  implements  are  packed  up  in  their  cafe  of 
black  fifh-fkin :  and  the  cover  of  the  lamp  is  reprefented 
by  fig.  ^12.] 

But  if  the  operator  has  the  double  bellows,  fig.  14. 
and  15.  he  fixes  them,  at  a  due  diftance,  to  the  fame 
table  by  the  brafs  clamp  y.  He  then  unfcrews  the 
blow-pipe  at  %  z,  joins  the  month  m  of  the  flexible 
tube  of  the  hemifphere  z  z,  paffing  each  orifice  thro* 
the  leather  tube  fig.  1 1 ,  and  tying  both  ends  with  a 
waxed  thin  pack-thread.  If  he  works  with  his  foot 
on  the  pedal,  the  ftring  of  which  is  feen  hanging  from 
the  end  of  the  bellows,  fig.  15.  (and  is  always  up,  on 
account  of  the  weight  <?),  then  the  air  is  abforbed  by 
the  bellows  fig.  15.  from  whence  it  is  propelled  by 
the  motion  of  the  foot  on  the  pedal  to  the  bellows, 
fig.  14.  whofe  conftant  weight  r  drives  it  out  through 
the  flexible  pipe,  fig,  10.  it  of  courfe  enters  the 
curved  part  z»/  of  the  blow-pipe,  and  drives  the  flame 
on  the  piece  m  of  the  ore,  that  is  to  be  examined  upon 
the  charcoal. 

{N.  B.  i.  This  double  bellows  is  packed  up  by  it* 
felf  in  a  mahogany  cafe,  about  9  inches  long.  6 ~  wide, 
and  about  3^  deep,  outfide  meafure.  2.  The  laft 
blowing  bellows,  fig.  1 4,  has  an  infide  valve^  which 
opens  when  the  upper  furface  of  it  is  at  its  greatelt 
height ;  in  order  to  let  the  fuperfluous  air  efcape  out, 
as  it  would  ctherwife  iflue  with  great  velocity  out  o£ 
the  tube,  fig,  1 1.  and  fpoil  the  operation.] 

If  the  operator  choofes  to  apply  the  vital  or  dephlo- 

gifticated  air  in  his  procefs,  let  him  fill  the  glafs-jar  h9 

fig.    17.  with  this  air;     and  put  it  within  the   tube 

marked  by  abzs,  filled  with  water,  fattening  the  neck 

E  of 


C    3«    ] 

of  the  jar  within  by  a  crofs-board  «/,  which  has  a 
hole  in  it  for  thatpurpofe  :  then  introducing  the  two 
ends  of  the  flexible  hollow  tube,  fig.  16.  both  to  the 
mouth  of  the  jar  and  to  the  hole  of  the  bellows  fig.  15. 
he  opens  the  hole  m  of  the  jar,  that  was  flopped 
with  the  ftopple  n  ;  the  column  of  the  water  palfes  in 
through  w,  and  forces  up  the  vital  air,  which  enters 
the  bellows,  and  of  courfe,  by  the  alternate  motion 
of  the  pedal,  paiTes  through  the  end  of  the  blow-pipe, 
to  urge  the  flame  upon  the  piece  of  ore  m,  fig.  2.  on 
the  charcoal  g.  But  the  dephlogifticated  air  may  be 
jilib  received  at  the  fame  time  that  it  is  produced,  by 
tying  the  pipe,,  fig.  16.  to  the  mouth  of  an  earthen 
retort,  or  even  of  a  glafs  retort  well-coated,  accord 
ing  to  the  method  of  Mr  Willis,  defcribed  in  the 
Tranfaclions  of  the  Society  of  Arts,  Vol.  V.  p.  96. 
This  laft  confifts  in  diflblving  two  ounces  of  borax  in 
a.  pint  of  boiling  water,  and  adding  to  the  folution  as 
much  flacked  lime  as  is  neeeflaiyto  form  a  thin  pafte. 
This  glafs  retort  is  to  be  covered  all  over  with  it,  by 
means  of  a  painter's  brufli,  and  then  fuffered  to  dry. 
It  -mutt  then  be  covered  wTith  a  thin  pafte  made  of 
linfeed  oil  and  Hacked  lime,  except  the  necfc  that  en 
ters  into  the  receiver.  In  two  or  three  days  it  will 
dry  of  itfelf ;  and  the  retort  will  then  bear  the  great- 
eft  fire  without  cracking.  Two  ounces  of  good  nitre 
being  urged  in  the  retort,  by  a  good  fire  on  a  chafing - 
difh,  will  afford  about  700  or  800  ounce-meafures  of 
dephlogifticated  air. 

To  make,  any  other  kind  of  chemical  afTays,  the 
^forceps  of  fig.  2.  which  fupports  the  charcoal,  is  ta 
ken  off  by  unfcrewing  thefcrew^;  the  blow-pipe  is 
alfo  taken  off,  by  loofening  the  fcrew  n  ;  the  hoop  fig. 
7.  is  put  in  its  place,  where  the  metallic  bafin  of  fig.  19, 
is  put  filled  with  fand  ;  the  piece  of  fig.  8,  is  fet  on  the 
other  pillar  r,r,  fig.  i.  to  hold  the  matrafs,  fig.  18.  up 
right,  or  the  receiver  fig.  20,  &c. 

Jn 


[     39     ] 

In  the  fame  manner,  the  retort,  fig.  9.  may  be  pat 
in  the  fand-bath  inftead  of  the  matrafs,  with  its  re 
ceiver  fig.  20.  which  may  bs  fupported  on  a  bit  of 
cork  or  wood,  hollowed  to  its  figure,  and  held  by  the 
pliers,  inftead  of  the  charcoal  fig.  2. 

But  if  the  operation  is  to  be  made  in  the  naked 
fire,  the  neck  of  the  retort,  fig.  9.  being  luted  to  the 
receiver,  or  balloon,  fig.  20.  may  be  Jianged  by  a  little 
chain  with  its  ring  over  the  flame,  being  fufpended 
from  the  piece  of  fig.  7.  or  8.  fcrewed  to  either  of  the 
pillars  as  may  be  molt  convenient.  Otherwife  the 
receiver,  fig.  20.  may  be  fupported  by  the  round  hoop 
of  brafs,  fig.  8.  or  7.  fcrewed  at  a  proper  height  to  ths 
pillar,  fig.  i.  tying  round  it  fome  packthread  to  de 
fend  the  glafs  from  the  contact  with  the  metallic  fup- 
port. 

The  piece  of  fig.  6.  may  bs  fcrewed  by  its  collar 
and  {crew  efto  any  of  the  pillars  ;  carrying  with  it  the 
retort  and  us  receiver,  at  proper  did.mces,  higher  or 
nearer  to  the  lamp  according  as  the  iUme  is  more  or 
lefs  violent. 

It  eaiily  may  be  conceived,  that  thefe  implements 
afford  all  forts  of  conveniences  for  making  any  kind 
of  fmall  operations  and  affays  in  miniature,  provided 
the  operator  pays  a  proper  attention  to  the  difpofition 
requifite  for  each  procefs  or  operation. 

Every  glafs  retort,  receiver,  matrafs,  bafon,  fmall 
funnels,  &c.  are  made  by  the  lamp-workers,  thac 
blow  beads,  thermometers,  and  other  fmall  glafs  in- 
ftruments. 

It  is  directed  that  the  lamp  £,  fig.  3.  be  filled 
with  fpirit  of  wine,  becaufe  it  gives  no  difagreeable 
fmell,  and  does  not  produce  any  fuliginous  and  difa 
greeable  cruft  on  the  vefiels  as  oil  does  :  moreover, 
the  fpirit  gives  a  dry  flame,  without  fmoke,  and 
ftronger  than  oil ;  belides  the  fpots  and  difagreeable 
confequences  this  lad  caufes,  if  fplit,  &c.  M.  de 
Morveau  adds,  that  the  expence  of  fpirit  is  quite  in~ 
E  2  confide- 


[    4°     ] 

eonfiderable  ;  and  that  he  performed  in  eight  or  ten 
minutes,  with  this  apparatus,  various  diffolutions,  eva 
porations,  and  other  proceffes,  which  otherwife  would 
have  taken  more  than  three  hours,  with  the  expeVice 
only  of  two  or  three  halfpence  for  the  fpirit  of  wine, 
whilft  the  fuel  of  charcoal  would  have  coil  near  ten  or 
eleven  pence. 

4But  a  very  important  circumftance  is,  as  Morveau 
obferves  likewife,  that  many  philofophers  do  not  ap 
ply  themfelves  to  chemical  operations,  for  want  of  op 
portunity  of  having  a  laboratory  to  perform  them  :  it 
requiring  a  proper  room,  and  fuitable  expences  of 
many  large  furnaces,  retorts,  crucibles  and  numerous 
other  implements,  £c.  whilft  thefe  miniature  laborato 
ries  may  in  great  meafure  afford  the  fame  advantages  ; 
at  leaft  to  that  degree  of  fatisfadion  fufficient  to  afcer- 
•tain  tli«  contents  and  products  of  any  fubftance  that 
is  fubjected  to  trial :  for  with  this  fimple  apparatus 
a  man  of  fome  abilities  may,  without  any  embaraff- 
ment,  in  a  Very  fhort  time,  and  with  little  expence, 
perform  fuch  diftillations  as  require  a  reverberatcry  fur 
nace  ;  all  forts  of  proceffes,  digeftions,  and  evapora 
tions,  which  require  a  regular  fand  heat ;  he  may 
vary  his  experiments  or  trials,  and  multiply  them  to 
a  great  number  of  various  performances,  draw  up  his 
conclufions,  and  reafon  upon  them,  without  lofs  of 
time,  without  the  hinderance  of  long  preparations  to 
work  at  large.  And  even  when  fuch  large  works  are 
to  be  performed,  he  may  obferve  beforehand  various 
phenomena  of  fome  fubftances,  which  being  known  in 
time,  would  otherwife  impede  the  proceffes  at  large, 
or  make  them  fail  abfolutely  ;  and  all  this  without  the 
rifk  of  a  eonfiderable  lofs,  and  without  expofing  him- 
felf  to  a  great  fare,  Sec, 


PART  II. 


PART     II. 


ARRANGEMENT*    OF    MINERAL 
BODIES. 


i.  HE  bodies  belonging  to  the  mineral  kingdom  are- 
divided  into  four  different  clafTes,  viz. 

1.  Earths  -f ,  or  thofe  fubftances  which  are  not  duc 
tile,  are  moftly  indiifoluble  in  water  or  oil,  and 
preferve  their  conftitution  in  a  ftrong  heat. 

2.  Salts  :  thefe  diffolve  in  water,  and  give  it  a  tafte  ; 
and  when  the  quantity  of  water  required  to  keep 
them  in  difTolution  is  evaporated,  they  concrete 
again  into  folid  and  angular  bodies. 

3.  Iiiflammallesy  which  can  be  diflblved  in  oils,  but 
not  in  water,  and  are  inflammable. 

4.  Metals,  the  heavieft  of  all  bodies  ;  fome  of  which 
are  malleable,  and  fome  can  be  decompounded. 

Here,  however,  it  muft  be,  obferved,  that  thefe  claf- 

fes  are  unavoidably  blended  one  with  another;  and 

-     ,  E  3  therefore 


*  According  to  the  fyftem  of  Cronfledt -,  altered^*, 
augmented,  and  improved  from  the  Obfervations  of  } 
©ther  Mineralogies.  / 

f  By  earths,  the  author  (Mr  Cronftedt)  does  not 
mean  (ftriclly  fpeaking)  only  earths,  but  includes  un 
der  that  title  all  the  kinds  of  it  ones  or  foilils  not 
faline,  or  metallic. 


C   4*    ] 

therefore  fome  exceptions  muft  be  allowed  in  every 
one  of  them :  for  inllance,  in  the  firft  clafs,  the  calca 
reous  earth  is  in  fome  meafure  difibluble  in  water,  and 
pipe-clay  with  fome  others  diminifh  fomewhat  in  their 
bulk  when  kept  for  a  long  time  in  a  calcining  heat. 
In  the  third  clafs,  the  calx  of  arfenic  has  nearly  the 
fame  properties  as  falts  ;  and  there  is  no  poffible  defi 
nition  of  fait  that  can  exclude  the  arfenic,  though  at 
the  fame  time  it  is  impoiTible  to  arrange  it  elfewhere 
than  among  the  femimetals.     In  the  fourth  clafs  it  is 
to  be  obferved,  that  the  metals  and  femimetals,  per 
fect  or  imperfect,  have  not  the  fame  qualities  common 
to  them  all ;  becaufe  fome  of  them  may.be  calcined,, 
or  deprived  of  their  phlogifton,  in  the  fame  degree  of 
fire  in  which  others  are  not  in  the  lead  changed,  un- 
kfs-  particular  artifices  or  procefles  are  made  ufe  of: 
feme  of  them  alfo  may  be  made  malleable,  while  others 
are  by  no  means  to  be  rendered  fo.     That  the  convex 
farface  metals  take  after  being  melted,  is  a  quality  net 
Particularly  belonging  to  them,  becaufe  every  thing 
that  is  perfectly  fluid  in  the  fire,  and  has  no  attraction 
to  the  veffel  in  which  it  is  kept,  or  to  any  added  mat 
ter,  takes  the  fame  figure  ;  as  we  find  borax,  fat  fufi- 
lile  microcojmicum^  and  others  do,  when  melted  upon 
a  piece  of  charcoal :  therefore,  with  regard  to  all  that 
has  been  faid,  it  is  hardly  worth  while  to  invent  fuch 
definitions  as  fhall  include  feveral  fpecies  at  once  ;  we 
ought  rather  to  be    content  with  perfectly  knowing; 
them  feparately. 


CLASS  I.     EARTHS. 

EARTHS,  are  thofe  mineral  bodies,  not 'ductile,  for 
the  mo  ft  part  not  diifoluble  in  water  or  oils,  and  which 
preferve  th&'r  conftitution  ia  a  flrong  heat. 

\    Thefe 


E    43     3 

Thefe  bodies  are  here  arranged  accordiftg  to  their 
condiment  parts,  fo  far  as  hitherto  difcovered  ;  and  are 
divided  into  five  orders.  See  the  article  EARTH. 

Order  I.     CALCAREOUS   EARTHS  *. 

THE  properties  of  thefe  are  as  follow  : 
i.  Friability  and  falling  into  a  fine  white  powdeY 
after  calcination. 

2.  Par- 


*  Calcareous  earth  is  moil  commonly  found  in  tha 
form  of  lime-ftone  ;  hard,  compact,  and  of  various  co 
lours  ;  under  which  general  name  may  be  compre 
hended  all  the  different  kinds  of  marbles.  Near  Bath 
in  England  is  found  a  kind  of  grey  ftone,  rather  foft 
than  hard.  This  contains  calcareous  earth  in  a  mild 
ftate,  and  likewife  fome  in  a  ftate  of  caufticity  :  hence, 
when  newly  dug  out  of  the  earth,  it  will  dilfolve  ful- 
phur,  or  make  lime-water  without  any  calcination. 
By  attraction  of  fixed  air  from  the  atmofphere,  it  foon 
hardens  after  it  has  been  dug  up. 

Mr  Williams  divides  the  lime-Hones  of  Scotland  into 
the  following  fpecies  : 

1 .  Grey,  whitifh,  and  pure  white  ;  regularly  Gratifi 
ed  ;   of  a  granulated  texture  ;  and  much  ufed  in  the 
Highlands  for  building  bridges.      Some  of  it  is  com- 
pofed  of  fine  glittering  fpangles  like  the  fcales  of  fifties  ; 
and  fome  is  as  pure  white  as  the  bell  refined  fugar, 
which  kind  he  thinks  may  be  called  Parian  marble. 

2.  Coarfe-looking    grey  mountain  lime  ftone,    hard 
and'ftrong,  of  a  granulated  texture,  difficult  to  work, 
in  fome 'places  rough  and  unequal,  in  others  fmooth 
and  even.      Sometimes  regtraiiy  ftratified,  at  other 
times- appearing  like  one  vail  irregular  bed  or  rock,  of 
various  thic  .u  .ics. 

3.  Aih-coL  ured  mru  -tain  I'm^ftones,  confiftihg1   of 
finall  giaJEb  of  a  fine  iinootli  :.  xtuie, ;  when  broken  re- 

icmbling 


[     44     3 

2.  Partial  folution  in  water,  with  which  they  con 
tract  great  heat,  and  by  fprinkling  with  water  they  fall 
more  readily  into  powder. 

3.  Infufibility  without  addition. 

4.  They 


fembling  flint.  In  the  Highlands  there  are  hills  of 
this  kind  of  ftone,  which  our  author  informs  us  he 
has  feen ;  fome  of  which  have  regular  ftrata,  while 
others  appear  in  one  vaft  mafs  like  a  rock  of  granite. 

4.  Regularly-ftratified  limeftone,  found  in  the  low 
countries,  exhibiting  a  vaft  variety  of  colours  ;  as  black, 
blue,  grey,  brown,  purple,  red,  and  afh -coloured  ;  with 
various  mixture?,  of  all  degrees  of  hardnefs  and  purity. 

5.  Limeftone  accompanying  coal,  and  frequently  the 
immediate  roof  of  the  vein.  This  likewife  fhows  a  great 
variety  of  colour,  texture,  and  quality ;  fome  being  fo 
much  adulterated  with  clay  and  other  heterogeneous 
mixtures  as  to  be  good  for  nothing,  while  others  are 
very  pure  and  fine.  Thefe  limeftones  are  always  found 
in  regular  ftrata.     "  They  are  found  (fays  our  author) 
as  regular  as  the  coals  they  accompany  ;  and  the  coal- 
ftrata  are  more  regular  in  continuation  upon  the  bear 
ing,  as  far  as  the  clafs  of  ftrata  belonging  to  the  coal 
reaches,  than  any  Other  that  I  have  inveftigated  ;  and 
I  look  upon  it,  that  this  obfervation  may  be  of  uie  in 
praaice." 

For  difcovering  limeftone  at  fome  dl fiance,  Mr 
Williams  gives  the  following  directions : — Let  them 
keep  the  line  of  ftretch,  or  bearing  of  the  ftrata ;  and 
in  the  coal-country,  they  will  be  fure  to  difcover  it 
at  nearly  the  fame  parallel  diitance  from  a  feam  of  coal  > 
or  other  given  ftratum,  as  the  place  where  it  was  laft 
feen.  But  many  of  the  mountain-limeftones  are  not 
much  to  be  depended  on.  Though  you  may  have, 
a  good  and  plentiful  quarry  in  one  place,  yet,  perhaps,, 
fcaif  a  mile,  or  half  a  quarter  of  a  mile  farther  for* 


C    45     ] 

4.  They  attract  the  fixed  air  from  the  vegetable 
and  mineral  alkalies,  and  thus  rendering  them  much 
more  caultic,  becoming  at  the  fame  time  mild  them-, 
feives. 

5.  Solu- 


ward,  you  cannot  difcover  it :  it  is  dwindled  away  to 
nothing,  and  yet  will  appear  again  farther  forward ; 
which  makes  the  mountain-limeftones  uncertain  to  be 
difcovered  where  you  do  not  fee  them ;  as  thefe  rocks 
very  frequently  grow  thicker  or  thinner,  and  fometimes 
fqueezes  out  to  nothing  :  and  I  comprehend  under 
this  denomination  all  the  limeftones  not  accompanying 
the  coals  and  coal-metals. — The  limeftcnes.of  the  coal 
fields  are  often  diftinguiihable  by  containing  a  great  va 
riety  of  fhells,  coral,  and  other  marine  bodies,  which 
are  found  blended  in  the  heart  and  compofition  of  the 
ftone." 

6.  The  Scotch  marbles  are  of  great  variety  and  beau 
ty  ;  and  the  parts  of  the  kingdom  moft  unfit  for  cul 
tivation  are  found  to  abound  moft  in  them.  Affint  in  Su 
therland  has  a  kind  of  white  ftatuary  marble,  which  Mr 
Williams  fays  is  the  pureft  and  bed  he  ever  faw.  "  I  am 
perluaded  (fays  he)  there  is  none  better,  if  any  fo  good, 
in  all  Europe,  and  there  is  enough  of  it  to  ferve  all  Bri 
tain  ;  perfectly  folid  and  pure,  free  of  any  blemifnes, 
flaws,  or  {tains,  and  blocks  or  {labs  of  any  fize  may  be 
cut  out :  but  there  is  bad  accefs  to  it ;  nor  would  it  be 
eafily  quarried,  there  being  a  little  cover  above  it,  of  a 
foft,  loofe,  whitifh  limeftone.  This  marble  accompa 
nies  a  prodigious  rock  of  grey  limeftone,  of  a  granula 
ted  texture,  appearing  in  regular  ftrata  at  Affint ;  but 
it  is  one  of  thofe  which  varies  in  thicknefs  as  you  advance 
along  the  bearing  of  the  ftrata.  The  good  white  mar 
ble  of  Affint  is  only  to  be  feen  in  the  bed  of  the  river, 
near  a  confiderable  houfe  a  mile  or  two  fouth  of  the 

church ; 


C    46    ] 

5.  Solubility  in  all  acids  except  the  vitriolic,  tarta* 
rous,  and  fome  anamalous  vegetable  acids. 

6.  Fufibility  with  borax  and  microcofmic  falts. — 
The  fufion  is  attended  with  effervefcence,  and  the  re- 
fult  is  a  tranfparent  and  colourlefs  glafs. 

7.  With  metalline  calces  they  melt  into  a  corrofive 
flag. 


church ;  but  I  cannot  remember  the  name  of  the  parti 
cular  place." 

Near  Blairgourie  in  Perthfhire,  not  far  from  the 
fide  of  the  high  road,  is  an  excellent,  granulated, 
broad-bedded  limeflone,  of  a  fugar-loaf  texture,  and 
as  white  as  the  fineft  ftatuary  marble,  which  Mr 
Williams  fuppofes  to  be  a  good  fpecies  of  the  true 
Parian  marble,  and  that  it  requires  only  to  be  known 
and  brought  into  ufe  to  become  of  great  value,  In 
the  duke  of  Gordon's  lands,  in  the  foreft  of  Gle- 
navon,  there  is  alfo  a  kind  of  marble  compofed  of 
broad  glittering  grains  like  fpangles,  as  large  as  the 
fcales  of  fifhes  j  but  the  fituation  is  remote,  and  dif- 
cult  of  accefs. 

In  Lochaber,  near  the  farm-houfes  on  the  north 
fide  of  the  ferry  of  Ballachyliih,  is  a  limeftone  or 
marble  rock,  of  a  beautiful  aflien-grey  colour,  and  a 
fine  regular  uniform  grain  or  texture ;  capable  of  be 
ing  railed  in  blocks  or  flabs  of  any  fize,  and  of  receiv 
ing  a  fine  polifh.  It  is  beautifully  fprinkled  with  fire 
bright  grains  of  mundick  or  pyrites,  and  likewife  with 
grains  or  fpecks  of  beautiful  lead  ore  of  a  fine  texture. 

About  three  miles  fouth  of  Fort-William,  in  the 
bed  of  a  river,  is  a  curious  kind  of  marble  with  a 
black  ground,  flowered  with  white,  like  fine  needle 
work,  or  rather  refemb'Jng  the  froft-flowering  upon 
glafs  windows  in  winter ;  and  this  flowering  is  not 
only  on  the  outfide,  but  quite  through  all  parts  of  the 
Jx>dy  of  the  ftone. 

Scotland 


E    47     3 

8.  They  imperfectly  reduce  the  calces  of  lead  and 
bifmuth,  and  have  even  fome  effect  upon  thofe  of  cop 
per  and  iron. 

The  cajcareous  earth  is  found, 
I.  Pure. 

1 .  In  form  of  powder.  Agaricu?  mineralis,  or  lac  lun£. 

a.  White,  in  moors,  and  at  the  bottom  of  lakes. 

b.  Red. 

c.  Yellow. 

2.  Friable  and  compact.     Chalk,  creta. 

a.  White,  creta  alba-.  Chalk  is  a  name  alfo  applied 
to  other  ea/ths  ;  whence  we  hear  of  chalks  of  va 
rious  colours :  but  there  are  none  which  are 
known  to  be  of  a  calcareous  nature,  except  this 
kind  here  defcribed,  and  of  which  there  are  no 
other  varieties,  otherwife  than  in  regard  to  the 
loofenefs  of  the  texture,  or  the  finenefs  of  the 
particles. 

3,  Indurated,  or  hard  ;  Limeftone  ;  Lapis  calcareus. 
A.  Solid,  or  not  granulated. 
a.  White. 
£.  Whitifh  yellow. 

c.  Flefh-coloured,  found  in  loofe  mafTes. 

d.  Reddifh  brown. 

e.  Grey. 

/.  Variegated  with  many  colours,  and  particular 
ly  called  marble. 
g.   Black. 
JB.  Grained  or  granulated  limeftone. 

i .  Coarfe-grained,  and  of  a  loofe  texture,  called 
fah-jtag  in  Swedifh,  from  its  refemblance  to 
kimps  of  fait.  \ 

a.  Red. 


Scotland  has  alfo  chalk  in  abundance  ;  fome  of 
vhich  is  regularly  ftratified,  and  much  appears  in  thick 
rregular  maffes  like  fediment. 


[     48     ] 

a.  ReddiiK  yellow,     b.  White. 

2.  Fine  grained. 

a.  White,  b.  Semi-tranfparent,  from  Solfatara 
in  Italy,  in  which  native  brimftone  is  found. 

3.  Very  fine  grained. 

a.  White  and  green.     I.  White  and  black. 
C*  Scaly  limeftone. 

1.  With  coarfe  or  large  fcales. 

a.  White,     b.  Reddifh  yellow. 

2.  With  fmall  fcales. 
a.  White. 

3.  Fine  glittering  or  fparkling. 

a.  White,     b.  Of  many  colours. 
ZX  Lime  or  calcareous  fpars. 

(i.)  Of  a  rhomboidal  figure. 
&.  Tranfparent  or  diaphanous. 

1.  Refracting   fpar ;    Spatum  ijlandicum ;   Iceland 
fpar,  or  Iceland  cryftal. — This  reprefents  the 
objects  feen  through  it  double. 

2.  Common  fpar,  which  fhows  the  object  fingle. 
#.  White,  or  colourlefs. 

b.  Yellowifli  and  phofphorefcent. 
u.  Opaaue. 

i.  White.     2.  Black.     3.  Brownifh  yellow. 
(2.)  Foliated  or  plated  fpar. 

a.  Opaque  white. 

j£.  Cryftallized  calcareous  fpars.     Spar.  Drufcn  *. 
(i.)   Traniparent. 

a.  Hexagonal  truncated. 
I.  Pyramidal. 

I .  Dog's  teeth  ;  Pyramldales  SJlinftix. 

2.  Balls 


*  The  tranflator  of  Mr  Cronftedt's  Treatife  has 
adopted  -this  German  term  drufcn  into  the  Englifti  lan 
guage,  for  a  clufter  of  regular  figured  bodies,  as  a 
groupe  conveys  the  idea  of  a  clr.fter  only,  whether 
regular  or  of  indeterminate  figures. 


C    49    ] 

2.  Balls  of  cryftallized  fpar,  Pyramldales  concrete. 
Jp.  Staladlitical  fpar  ;  Sta'aSites  calcareus*     Stalactites^ 

Stone-icicle,  or  Drop-ftone. 
( i.)   Scaled  ftala&ites  of  very  fine  particles. 

a.  Of  a  globular  form. 
^.  White,  the  pea-ftone. 

2.  Grey,  plfiKthus,  oolithm.  Alfb  the  hammites, 
from  its  refemblance  to  the  roes  or  fpawn  of 
fifh.  It  has  been  exhibited  by  authors  as  petri 
fied  roes.  The  Ketton  free-fione,  of  Rutland* 
fhire,  is  a  remarkable  (lone  of  this  fort. 

b.  Hollow,  in  the  form  of  a  cone* 
i.  White. 

c.  Of  an  indeterminate  figure. 

d.  Of  coherent  hollow  cones. 

(2.)  Solid  ftalactites  of  a  fparry  texture. 

a.  Hollow,  and  in  form  of  a  cone. 
i.  White,  and  femitranfparent. 

II.  Saturated  or  combined  with  the  acid  of  Vitriol. 
Gypfum,  Plafter-ftone,  or  Parget. 

1.  Loofer  and  more  friable  than  a  pure  calcareous 
earth. 

2.  Either  crude  or  burnt,  it  does  not  excite  any  ef- 
fervefcence  with  acids  ;  or,  at  moft,  it  effervefces 
but  in  a  very  flight  degree,  and  then  only  in  pro 
portion  as  it  wants  fome  of  the  vitriolic  acid  to 
complete  the  faturation. 

3.  It  readily  falls  into  a  powder  in  the  fire. 

4.  If  burnt,  without  being  red  hot,  its  powder  rea 
dily  concretes  with  water  into  a  mafs,  which  fooa 
hardens  ;  and  then, 

5.  No  heat  is  perceived  in  the  operation. 

6.  It  is  nearly  as  difficult  to  be  melted  by  itfelf  as 
the  limellone,  and  fhows  moftly  the  fame  effecls 
with  other  bodies  as  the  lime-ftone :  the  acid  o£ 
vitriol  feems,  however,  to  promote  its  vitrifica 
tion. 

F  7,  Whea 


C   5°   3 

7.  When  melted   in  the   fire  with  borax,   it  puffs 
and  bubbles  very  much,  and  for  a  long  while, 
during  the  fufion,  owing  to  the  nature  cf"  both  the 
falts. 

8.  When  a  fmall  quantity  of  any  gypfum  is  melted 
together  with  borax,  the  glafs  becomes   colour- 
lefs  and  tranfparent ;  but  fome  forts  of  alabafter 
and  fparry  gypfa,  when  melted  in  fome  quan 
tity  with  borax,  yield  a  fine  tranfparent  yellow 
coloured  glafs,    refembling  that  of  the  bed  to 
pazes.     This  phenomenon  might  probably  hap 
pen  with  every  one  of  the  gypfeous  kind.     But  it 
is  to  be  obferved,  that  if  too  much  of  fuch  gyp 
fum  is  ufed  in  proportion  to  the  borax,  the  glafs 
becomes  opaque,  juft  as  it  happens  with  the  pure 
limeftone. 

9.  Burnt  with  any  inflammable  matter,  it  emits  a 
fulphureous   fmell  ;    and  may  as    well   by  that 
means,  as  by  both  the  alkaline  falts,  be  decom 
pounded  ;  but  for  this  purpofe  there  ought  to  be 
five  or  fix  times  as  much  weight  of  lalt  as  of 
gypfum. 

10.  Being  thus  decompounded,  the  calx  or  earth 
which  is  left  iliows  commonly  fome  marks  of  iron. 

The  gypfeous  earth  is  found, 

(i.)  Loofe  and  friable.     Gypfeous  earth,  properly  fo 

called  ;  Guhr. 

A.  White. 
(2.)   Indurated. 

A.  Solid,  or  of  no  vifible  particles,  Alabafter. 
a.  White,  alabafter. 

1.  Clear  and  tranfparent. 

2.  Opaque, 
£.  Yellow. 

i.  Tranfparent,  from  the  Eaftern  countries. 
2»  Opaque. 

B.  Gypfum  of  a  fcalded  or  granulated  ftru&ure. 
This  is  the  common  plafter-ftone. 

j.  With 


[     5'     ] 

1.  With  coarfe  fcales.     a.  White. 

2.  With  fmall  fcales.     a.  Yellowifh.     I.  Greyifh. 
C.   Fibrous  gypfum,    or    plafter-ftone,  improperly 

(though  commonly)    called  Englijh  talc  by  the 
druggifts. 

i.  With  the  fibres  coarfe.     a.  White,  from  Li 
vonia. 

-      TXfM,    r,^o  £Tvpc          n      Whi^P. 

X).  Spar-like  gypfum.  Selenites,  by  feme  alfo  call 
ed  gtacies  mat  1,2  ;  and  confounded  with  the  ckar 
and  tranfparent  mica. 

1.  Pure  felenites. 
A.  Tranfparent. 

a.  Colourlefs.     I.  Yellowiili. 

2.  Liverftonc,  fo  called  by  the  Swedes  and  Ger 
mans. 

£.  Cryftallized  gypfum.     Gypfecus  drufen. 

(  i  ).   Drufen  of  chryftals  of  pure  fparry  gypfurn. 

A.  Wedge  formed,   ccmpofed  of  a  purs  fpar- 
like  gypfum. 

a.  Clear  and  colourlefs.     b.  V/hitifh  yellow. 

B.  Capillary. 

a.  Opaque  whitifh  yellow,     t.  Hexagonal, 
prifmatic.    c.  Globular,  confjfting  of  ciuie- 
ated  rays  proceeding  from  the  centre, 
F.  Stalaclitical  gypfum.      Gypfum  finter. 

j .  Of  no  vifible  particles  ;  in  French,  grignard. 
A.  Of  an  irregular  figure. 
a.  Yellow,     b.  White. 
2.  Of  a  fpar-like  texture. 

A.  In  form  of  a  cone. 
a.  White  and  yellow. 

B.  Of  an  irregular  figure. 
a.  White. 

III.  Calcareous  earth  faturated  with  the  acid  of  com 
mon  fait.      Sal  ammoniacumjixum  nalurale. 

This  is  found,  i.  In  fea-water.     2.  In  fait  pits. 

F  2  IV.  Cal- 


C    !'     ] 

IV.  Calcareous  earth  combined  or  faturated  with  fpany 
acid,  known  by  die  name  of  f parry  Jluor  and  Hue 
John. 

Thefe  are  commonly  caUed^«xi«^w/r^«/,  org/afs- 
fpars  ;  bccaufe  mod  part  of  them  have  a  fparry  form 
and  appearance  :  they  are,  however,  often  met  in  an 
intkterniinate  figure. 

They  are  only  known  m  an  indurated  itate,  and  di- 

ftingujfh  themfelves  from  the  other  earths  by  the  fol 
lowing  characters. 

1.  They  are  fcarce  harder  than  common  calcareous 
fpars,  and  confequently   do  not  ftrike  fire  with 
Heel. 

2.  They  do  not  ferment  with  acids  neither  before 
nor  after  calcination. 

3.  They  do  not  melt  by  themfelves,  but  crack  and 
fplit  to  pieces  when  expofed  to  a  ftrong  fire.   But, 

4.  In  mixtures  with  all  other  earths  they  are  (ge 
nerally)  very  fufible,  and  efpecially  with  calca 
reous  earth,  with  which  they  melt  into  a  corro 
ding  glufs  that  diffclves  the  ftrongeft  crucibles, 
unlefs   fome   quartz  or  apyrous  clay   be  added 
thereto. 

5.  When  heated  {lowly,  and  by  degrees,  they  give 
a  phofphorefcent  light :  but  as  foon  as  they  are 
made  red-hot,  they  loofe  this  quality.     The  co 
loured  ones,  efpecially  the  green,  give  the  ftron- 
geft  light,  but  none  of  them  any  longer  than  whilft 
they  are  well  warm. 

6.  They  melt  and  diflblve  very  eafily  by  the  addi 
tion  of  borax  ,  and,  next  to  that,  by  the  micro- 
cofmic  fait,  without  ebullition. 

A*  Indurated  fluor. 

(i.)  Solid,  of  an  indeterminate  figure;  of  a  dull 
texture,  femitranfparent,  and  full  of  cracks  in  the 
rock. 

a.  White. 

(2.)  Sparry 


C    53     ] 

(2.)  Sparry  fluor.  This  has  nearly  the  figure  of 
fpar  ;  though  on  clofe  obfervation  it  is  found  not 
to  be  fo  regular,  nothing  but  the  gloffy  fur  faces 
of  this  (tone  giving  it  the  refemblance  of  fpar. 

a.  White,  b.     Blue.  c.  Violet,  d.  Beep  green. 
e.  Pale  green.    /.  Yellow. 

(3.)  Cryftallifed  fluor. 

1.  Of  an  irregular  figure,     a.  White.     I.  Blue. 
c.  Red. 

2.  Of  a  cubical  figure,     a.  Yellow.     I.  Violet. 
4.  Of  a    polygonal  fpkerical  nVure.     a.  White. 

b.  Blue. 

4  Of  an  o^loedral  figure,     a.  Clear,  colourlefs. 

V.  Calcareous  earth  faturated  with  a  particular  acid, 

perhaps  of  the  metallic  kind,  viz.  the  tungftenic 

acid.  The  tungjleln  of  the  Swedes. 
This  refembles  the  garnet-ftone  and  the  tin-grains ; 
is  nearly  as  heavy  as  pure  tin ;  very  refractory  in  the 
air,  and  exceffively  difficult  to  reduce  to  metal.  Iron 
has,  however,  been  melted  out  of  it  to  more  than  30 
per  cent.  It  is  very  difficultly  diflblved  by  borax  and 
alkaline  falts,  but  melts  very  eafily  with  the  microcof- 
mic  fait,  giving  a  black  ilag ;  and  for  this  reafon  the 
lad  mentioned  fait  muft  be  employed  in  the  aifays  of 
this  ftone.  It  is  found, 

1.  Solid  and  fine-grained. 

a.  Reddifh  or  fbfh-colcured.     I.  Yellow. 

2.  Spathofe,  and  with  an  undluous  furface. 
a.  White,     b.  Pearl-coloured., 

VI.  Calcareous  earth  united  with  the  inflammable  fub* 

(lance. 

Thefe  have  a  very  offenfive  fmell,  at  lead  when  rub 
bed.     They  receive  their  colour  from  the  phlogifton,, 
being  dark  or  black  in  proportion  as  it  predominates, 
(i.)  Calcareous  earth  mixed  with  phlogifton  alone  ; 
Lapis  fui/lus,  fetid  ftone  and  fpar,  or  fwine-ftone 
and  fpar, 

F  d.  £elid> 


C    54    1 

v/.  Solid,  or  of  no  viiible  or  diflinct  particles. 

a.  Black. 
JB.  Grained. 

a.  Blackifh  brown. 

C.  Scaly,  partlculis  micaceis* 

1.  With  coarfe  fcales.     a.  Black. 

2.  With  fine  fparkling  fcales.     a.  Brown. 

D.  Sparry. 

a.  Black.     I.  Light  brown,     c.     Whitifh  yellow* 

E.  Cryftallifed. 

i.  In  a  globular  form. 

VII.  Calcareous  earths  blended  with  an  argillaceous 
earth.     Marie,  Marga. 

1.  When    crude,  it  makes    an    effervefcence  with 
acids:  but, 

2.  Not  after  having  been  burnt ;  by  which  opera 
tion  it  is  obferved  to  harden,  in  proportion  as 
the  clay  exceeds  the  calcareous  fubftance. 

3»  It  eafily  melts  by  itfelf  into  a  glafs,  and  even 
when  it  is  mixed  with  the  moft  refraftory  clay. 

4.  It  is  of  great  life  in  promoting  the  growth  of 
vegetables,  fmce  the  clay  tempers  the  drying  qua 
lity  of  the  calcareous  earth. 

5.  When  burnt  in  a  calcining  heat,  it  readily  attracts 
water  :  and,  expcfed  to  the  air,  in  time  it  falls 

•   into  a  powder. 

The  varieties  of  this  kind  worthy  to  be  taken 
notice  of,  depend  on  the  different  quantities  of 
each  of  their  component  parts,  and  on  the  quality 
of  the  clay.  The  following  are  fpecified  as  ex 
amples. 

A.  Loofe  and  compadl,  Marga  fnabiTis. 
a.  Reddifh  brown. 

I.  Pale  red.  This,  when  burnt,  is  of  a  yellowifli 
colour,  and  ufed  for  making  earthen  ware  in 
fome  places. 

J].  Semi-indurated  ;  which  is  nearly  as  hard  as  ftone 
when  firft  dug  up,  but  moulders  m  the.o.pen  air, 

&.  Grey. 


C    5J     ] 

a.  Grey.     I.  Red. 
C.  Indurated  or  ftone  marie. 

A.  in  loofe  pieces,  Marga  tndurata  amorpha  ;  by 
the  Germans  called  duckjlem  or  topbjkin* 

<7.  White,     b.  Grey,  formed  from  a  fediment 
•which  the  water  carries  along  with  it. 

B.  In  continued  ftrata.     Hard  ilaty  marie. 

VIII.  Calcareous  earth  united  with  a  metallic  calx. 

Here,  as  well  as  in  the  others,  fuch  a  mixture  or 
combination  is  to  be  underftood,  as  cannot  be  difco- 
vered  by  the  eye  alone  without  the  help  of  fome  other 
means. 

The  fubjefts  belonging  to  this  divifion  lofe  the  pro 
perty  of  raifing  an  effervefcence  with  acids,  when  they 
are  rich  in  metal,  or  contain  any  vitriolic  acid.  How 
ever,  there  have  been  found  fome  that  contained  20 
or  30  per  cent,  of  metal,  and  yet  have  fhoun  their  cal 
careous  nature  by  the  nitrous  acid. 

There  are  no  more  than  three  metals  hitherto  known 
to  be  united  in  this  manner  with  the  calcareous  earth, 
•viz. 

( i )  With  iron.  White  fpar  like  iron  ore,  Mlnera 
Jerri  alia.  The  jtahlftein  or  tuelfes  eifenerz,  of  the 
Germans. 

1.  This  ore,  however,  is  not  always  white,  but 
commonly  gives  a  white  powder  when  rubbed. 

2.  It  becomes  black  in  the  open  air,  as  likewife  in 
a  calcining  heat. 

3.  In  this  laft  circumftance  it  lofes  30  or  40  per 
cent,  of  its  weight,  which  by  diltillation    has 
been  found  owing  to  the  water  that  evaporates  ; 
and  it  is  poffible  that  fome  fmall  quantity  of 
vitriolic  acid  may,  at  the  fame  time,  evaporate 
with  the  water. 

» It  is  of  all  the  iron  ores  the  moft  eafy  to  melt, 
and  is  very  corrofive  when  melted. 

This, 


C   56   J 

This  kind  is  found, 

A.  Loofe ;  the  mouldered  part  of  the  indu 
rated  fort. 

a.  Black,  like  foot. 

b.  Dark  brown,  fomewhat  refembling  umbre. 

B.  Indurated. 

1.  Solid,  of  no  diftinft  particles. 

a.  Red.  Looks  like  red  ochre,  or  the 
red  haematites,  but  diflblves  in  the  acid 
of  nitre  with  a  great  effervefcence. 

2.  Scaly,  par  faults  micaceis. 
a.  White. 

I.  Blackifh  grey. 

3.  Spar-like. 

a.  Light  brown. 

4.  Drufen. 

a.  Blackifli  brown. 

b.  White. 

1.  Porous.     This  is  often  called  eifen- 
blute,  orjlosferri. 

2.  Cellular. 
(2)  With  copper. 

A*  Loofe  and  friable.  Mountain  blue ;  Germa- 
Ciice,  Bergllau.  This  diffolves  in  aquafortis 
^rith  effervefcence. 

B.  Indurated. 

1.  Pure  calcareous  earth  mixed  with  calx  of 
copper.     Armenian  fione,  lapis  Armenus. 

2.  Gypfeous  earth  united  with  calx  of  copper. 
Is  of  a  green  colour  ;  and  might  perhaps  be 
called  turquoife  ore,  or  malachites  ;  though  we 
do  not  know  if  all  forts  of  turquoife  ore  are 
of  this  nature. 

a.  Semi-tranfparent,  is  found  at  Ardal  in 

Norway. 
(3.)  With  the  calx  of  lead. 

This  is  a  lead  ochre,  or  a  fpar-like  lead-ore, 
which,  in  its  formation,  has  been  mixed  with  a 

calca- 


I    57     ] 

calcareous  earth,  and  for  that  reafon  eflervefces 
with  acids. 

A.  Loofe  and  friable, 
i.  White. 

B.  Indurated, 
i.  Scaly. 

tr    11          -t\ 

Boththefe  varieties  contain  a  considerable 
quantity  of  lead,  in*.  40  per  cent,  more  or 
lefs  ;*and  the  calcareous  earth,  is  as  equally 
and  intimately  mixed  with  it,  as  in  the  white 
iron  ore. 

IX.  The  following  compounds  of  calcareous  earth 
with  different  mineral  fubftances  are  added  from 
Mr  Kirwan's  Elements  of  Mineralogy. 

1.  A  compound  of  calcareous  and  barotical  earths  : 
of  this  fpecies  are  fome  yellowifh  ftones  found  in 
Derbyfliire,  confiding  of  lumps   of  limeftone  in- 
terfperfed  with  nodules  of  barofelenite.     Many 
more  may  occur  as  compounds  of  gypfum  and  ba 
rofelenite,  fluor  and  barofelenite,  &c.  &c. 

2.  Compounds  of  calcareous  and  magnefian  earths ; 
fuch  as, 

a.  The  white   marble,    interfperfed  with  fpots  of 
fteatites    of  foap-rock,    either   green    or  black, 
called  by  Crondftedt  kolmord  marble.     This  mar 
ble  is  of  a  fcaly  texture. 
1.  The  pletra  takhina  of  the  Italians,  which  confifts 

of  white  fpar  with  veins  of  talc. 
c.  The  verde  antico  of  the  Italians,  which  is  a  light 
green  marble,  with  deep  green,  black,  white, 
and  purple  fpots.  According  to  Mr  Bayen, 
it  contains  62  parts  of  mild  calcareous  earth, 
30  of  green  talc,  i  of  magnefia,  and  i  of  fe- 
miphlogifticated  iron. 

3.  Compounds  of  calcareous  and  argillaceous  earths; 
fuch  as, 

a.  The 


a.  The  green  Campan  marble  from  the  Pyrenees. 
It  is  flaty  and  fomewhat  magnetic.  Accord 
ing  to  Mr  Bayen,  it  contains  65  of  mild  calca 
reous  earth,  32  of  the  argillaceous,  and  3  of  fe» 
miphlogifticated  iron. 

£.  The  red  Campan  marble  :  this  is  not  magne- 

tUUJt  .contains  82  parts  of  mild  calcareous 
eann,   1 1  01  argmaxtuuo  imnu^,  «.nva  /  v>i  uv- 

phlogifticated  iron. 

t.  Yellow  figured  marble  from  Florence  :  accord 
ing  to  Mr  Bayen,  it  contains  75  parts  of  mild 
calcareous  earth,  13  or  14  of  fhiftus,  and  4  or 
5  of  dephlogifticated  iron. 

J<  Griutte  marble  from  Autun  of  Burgundy  in 
France  :  it  contains  67  parts  of  mild  calcare 
ous  earth,  26  of  reddifh  fchiftus,  2  of  iron, 
and  i  of  magnefian  earth. 

e.  The  Amandola,  which  is  a  green  marble,  ho 
ney-comb  like,  with  white  fpcts.  It  contains 
76  parts  of  mild  calcareous  earth,  20  of  fchiftus, 
and  2  of  femiphlogifticated  iron.  The  cellular 
appearance  proceeds  from  the  fchiftus. 
4*  Compounds  of  calcareous  earth  and  mica  ;  fuch 

as, 

a.  The  cipolin  from  Autnn  in  France :  it  is  of  a 
gree.n  colour,  and  confifts  of  83  parts  of  chalk, 
12  of  green  mica,  and  i  of  iron. 

b.  The  micaceous  limeftone,  is  of  a  glittering  ap 
pearance,  of  various  degrees  of  hardnefs,  and 
effervefces  with  acids.   Such  as  the  macigno  of 
the  Italians;  their  yelloxv  pietra   bigia;   and 
their  blue  pietra  columbina  or  turkina. 

5.  Compounds  of  calcareous  and  filiceous  earths  j 
fuch  as, 

a.  The  calcareous  quartz  and  pudding-flone  :  this 

confifts  of  lumps  of  quartz,  and  fometimes  of 

felt-fpar  in  a  calcareous  cement. 

I,  The  limeftone  with  veins  of  quartz ;  fuch  as 

\hzfaxumfahibergenfe,  and  feveral  marbles  of 

Sweden 


[    59     ] 

Sweden    and  Siberia,    which  ftrike  fire  with 

fteel. 

6.  Calcareous  volcanic  pudding-ftone ;  fuch  as, 
a.  The  cierchina,  which  confifts  of  lumps  of  fpar 

and  lava,  in  a  calcareous  cement,  mentioned  by 

Mr  Ferbei. 
I.  The  marble  mixed  with  veins  of  black  or  green 

lava,  mentioned  by  the  fame  anthor. 
r.  Compounds  of  calcareous  earth,  mixed  with  two 
or  more  kinds  of  earth  ;  fuch  as, 

a.  The   cipolin  from  Rome,  which  is  fa  green 
marble  with  white  zones :    it  ftrikes,  though 
difficultly,    fire    with  fteel :    it  contains    67,8 
parts  of  mild  chalk,  25  of  quartz,  8  of  fhiftus, 
andg|,2  of  iron,  befides  the  iron  contaiaed  in 
the  argillaceous  fhiftus. 

b.  The    calcareous  porphyry,    which  confifts  of 
quartz,  felt-fpar,  and  mica  in  feparate  grains 
united  by  a  calcareous  cement. 

c.  The   limeftonc    interfperfed  with  fhoerl  and 
mica. 

d.  To  thefe  compounds  belongs  the  pyritaceous 
lime  (tone  called  by  the  French  Pierre  de    Sf 
Ambroix.     It  is  of  an  iron  grey  colour,  inter 
fperfed  with  jQiining  particles.     Its  texture  is 
compact,  and  fcarcely  gives  fire  with  fteel.  Its 
fpecific  gravity  is  2,7034.  It  is  foluble  in  acids, 
and  moftly  with  elfervefcence  ;  calcines  in  a 
ftrong  fire ;    makes    nitre    flightly  detonate ; 
and  if  diftilled  affords  a  fmall  portion  of  vitrio 
lic  acid,  and  fome  fulphur  fublimes.     Its  com 
ponent  parts  are  75  of  mild  calcareous  earth 
and  25  of  pyrites;  in  which  are  contained  14 
of  argill,  7  of  quartz,   and  fulphur,  and  4  of 
iron. 

Order 


Order  II.  PONDEROUS  EARTH. 
PONDEROUS  earth,  (Terra  Ponderofa)  :  Cauk,  or 
calk.  See  EARTH,  Art.  I.  This  is  a  particular  kind 
of  earth  (like  chalk  in  appearance,  but  with  fome 
very  different  properties),  difcovered  in  Sweden  about 
1774,  which  by  its  refults  with  other  bodies  has  fome 
fimilarity  to  the  known  alkalis.  It  has  not  yet 
been  found  pure,  but  mixed  with  other  fubftances  : 
however,  its  great  fpecific  weight  eafily  diftinguilhes 
it  from  the  others,  it  being  the  heavieft  of  all  earths. 
i.  Its  fpecific  gravity  when  confiderably  purified 

by  art  is  3,773. 

a.  This  earth  combines  with  aerial  acid :  and  in 
this  cafe  effervefces  with  ftronger  ac^s. 

3.  With  vitriolic  acid  it  forms  the  ponaerous  fpar, 
which  is  mfoluble  in  water. 

4.  Its  cr/ftallization,  after  being  combined  with  the 
nitrous,  or  with  the  muriatic  acids,  is  hardly  fo- 
^uble ; 

5.  "b>c  with  acetous  acid,  it  becomes  deliquefcent. 

6.  When  pure  ;  viz.  without  any  mixture  of  acid  or 
alkali,  it  does  not  vitrify  in  the  fire. 

7.  If  deprived  of  the  aerial  acid  (fixed  air)  by  cal 
cination,  is  then  foluble  in  900  times  its  weight 
of  boiling  water..     This  folution  expofed  to  air, 
forms  a  cremor,  like  that  of  lime-water  in  the 
fame  circumftances,  and  like  it  changes  alfo  the 
vegetable  colours. 

8.  Whilft  combined  with  aerial  acid,  it  is  only  fo 
luble  in  about  1550  times  its  weight  of  water, 
chiefly  if  the  water  has  been  impregnated  alfo 
v/ith  the  fame  aerial  acid, 

9.  It  expels  the  cauflic  volatile  alkali  from  ammoni- 
acal  fait. 

10.  Mixed  with  brimftone  it  produces  a  hepar  ful- 
phuris,  whofe  folution  in  water  is  but  incomplete 
ly 


C     61     ] 

ly  decompofed  either  by  the  nitrous  or  the  muria 
tic  acid,  on  account  of  the  great  attraction  be 
tween  this  earth  and  the  acid  of  fulphur,  which  is 
fo  ftrong  that  it 

u.  Separates  this  acid  (the  vitriolic)  from  the  ve 
getable  alkali. 

I.  Combined  with  aerial  acid  ;  Terra  Ponderofa  aerata. 

See  CHEMISTRY-/«^V. 

It  refembles  alum,  but  is  hard  and  ftriated,  as  if 
compofed  of  radiating  fibres  coming  from  a  cen 
tre.     It  is  found  in  Alllon-moor  in  England. 
A.  Spar-like  gypfum. 

1.  Ssmitranfparent,  fpatum  Bononienfe.     The  Bono- 
nian  ftone,  or  native  phofphorus. 

2.  Opaque,     a.  White,     b.  Reddifh. 
J3.  Ponderous  Drufen  fpar. 

1.  Jagged,  crtftatum.     Thefe  refemble  cock's  combs, 
and  are  found  in  clefts  and  fiflures  accreted  on  the 
furfaces  of  balls  of  the  fame  fubftance. 

2.  White. 

3.  Reddifh. 

II.  United    with  phlogifton  and    the  vitriolic    acid. 

Leterjlein  of  the  Germans   and  Swedes.     Lapis 

hsfaticus. 
This  ftone  in    fome  fpecimens  conftantly,    but  in 

others  only  when  rubbed,  fmells  like  the  hepar 

fulphurls,  or  gun-powder. 
It  is  found. 

A.  Scaly. 

1.  With  coarfe  fcales.     a.  Whitifh  yellow. 

2.  With  fine  fparkling  fcales.     a.  Black. 


Order  III 


Order  III.     MAGNESIAN,  MICACEOUS,  and 
ASBESTINE  EARTHS. 

§  i.     Jftfagjufian  Earths. 

MAGNESIA  is  a  white,  loofe,  and  light  earth,  only 
known  fmce  the  beginning  of  this  century.  It  is  ge 
nerally  found  combined  or  mixed  with  other  hetero 
geneous  fubftances,  as  other  fimple  earths  are. 

1.  When    pure  its  fpecific  gravity  is  2,330,    and 
then, 

2.  It  neither  hardens,  contracts,  nor  melts  by  the 
application  of  heat,  even  by  the  folar  rays. 

3.  But  it  melts  eafily  with  borax,  or  microcofmic 
fait ;  though  it  is  fcarcely  affecled  by  fixed  alka 
lis  or  calces  of  lead. 

4.  Mixed  with  other  earths,  it  produces  by  fire  dif 
ferent  hard  mafTes. 

5.  It  gives  no  caufttcity   except  to  the  volatile  al 
kali  :  and, 

6.  Does  not  efFervefce  with  any  acid. 

7.  When  mixed  with  water  it  fhows   a  very  fmall 
degree  of  heat,  but  without  any    effervefcence. 
And  when  the    water  exceeds    the    weight    of 
magnefia  about  7,692    times,   it  is  totally    dif- 
folved. 

$  and  9.  Being  put  in  water  and  afterwards  dried, 
it  contains  •^L-/-u  parts  of  its  weight ;  though  when 
f  iturated  with  aerial  acid,  it  will  abforb  and  re 
tain  after  being  dried  T6/0.  parts  of  water. 

10.  This  earth  combined  \\ith  aerial  acid  is  more 
foluble  in  cold  than  in  hot  water. 

11.  Combined  with  vitriolic  acid  it  cryftallizes  into 
a  bitter  fait,  known   by  the  name   of  Epfom  and 
Seydlitz  or  Scidfchulitz  fait,  which  is  foluble  in  lit 
tle  more  than  its  own  vi  eight  of  water. 

12.  With  nitrous  acid  it  forms  a  del'-quefcent  fait. 

13.  With 


C    63    3 

13.  With  the  muriatic  or  the  acetous  acids- it  does 
not    cryftallize  :   and   the   mafs   being  dried,  at 
tracts  humidity  from  the  air. 

14.  It  has  a  ftronger  attraction   to  the  fluor  acid 
than  to  any  other  (Berg.) :   and  cryftaliizes  with- 
it  into  hexangular  priims  whofe  ends  are  formed 
of  two  low  pyramids,  of  three  rhombs  (Rome  de 
!'  IJk). 

15.  It  is  not  precipitated  from   other  acids  by  the 
vitriolic,  as  calcareous  earth  is. 

1 6.  According  to   Lavoifier   and    Macqner,  when 
magnefia  is  calcined,   it  becomes  phofphercicent. 

I.  Magnefia    combined     with    vitriolic     and    other 

acids. 

d.  When  fattirated  with  the  vitriolic  acid,  it  forms 
a  bitter  fait,  called  jEngli/b  or  Epfvm,  Seydftu?-* 
cr  Sedlit-x,  fait.  The  falts  known  under  thefe  d;f- 
ferent  names  only  differ  from  one  another  on  ac 
count  of  fome  heterogeneous  fuhftance,  which  is 
combined  in  them,  the  vitriolated  magnefia  be 
ing  the  characterise  and  principal  ingredient  in 
them  all. 

JB.  Magnefia  is  found  not  only  combined  with  the 
vitriolic  acid  in  the  waters  of  Epfom,  Sedlitz,  &c. 
but  alfo  with  the  marine  acid  to  a  confiderable 
quantity  in  fea-water  and  other  fait  fprings. 

C.  It  is  contained  frequently  in  frefh  waters,  where 
it  is  diifolved  by  means  of  a  quantity  of  aerial 
acid. 

II.  Combined  with  other  earths. 

A.  Magnefia,  when  combined  with  filiceous  earth, 
is  commonly  unctuous  to  the  touch,  and  more 
or  lefs  difficult  to  be  cut  or  turned  in  proportion 
to  its  different  degrees  of  hardnefs. 

It  is  not  diffufible  in  water:  grows  hard,  and 
is  very  refractory  in  the  fire. 

G  2  When 


C    64    ] 

When  pounded  and  mixed  with  water,  it  will 
not  eafily  cohere  into  a  pafte :  however,  if  it  is 
managed  with  care,  it  may  be  baked  in  the  fire 
to  a  mafs,  which  being  broken,  fhow^s  a  dull  and 
porous  texture. 

It  takes  for  the  moft  part,  and  without  much 
labour,  a  fine  polifh.     It  is  found, 
( i.)  Compact  and  foft ;  Smeftis,  Bnangon  or  French 
Chalk. 

a.  White,  from  the  Lands-End,  in  Cornwall, 

b.  Yellow. 

c.  Red  and  white,  from  the  Lands-End  -•  the  foap- 
earth,  from  Switzerland  :    it  looks  like  Caftile- 
foap. 

(2.)  Solid  and  compact ;  of  impalpable  particles: 
Steatites  or  foap-rock. 
a.  White,    or   light    green,     b.  Deep  green.— 

c.  Yellow. 

( 3. )  Solid,  and  of  vifible  particles  ;  ferpentine  flone. 
A.  Of  fibrous  and  coherent  particles. 
This  is  co/rpofed,  as  it  were,  of  fibres,  and  might 
therefore  be  confounded  with  the  afbeftus,  if  its 
fibres  did  not  cohere  fo  clofely  with  one  another, 
as  not  to  be  feen  when  the  ftone  is  cut  and  po- 
lifhed.  The  fibres  themfelves  are  large,  and  feem 
as  if  they  were  twifted. 

a.  Deep  green.  It  is  fold  for  the  lapis  nephriticus, 
and  is  dug  at  fome  unknown  place  in  Ger 
many,  b.  Light  green,  from  Skienfhyttan,  in 
Weftmanland ;  is  ufed  by  the  plate-fmiths  in- 
ftead  of  French  chalk. 

p.  Of  granulated  particles ;  fine  grained  ferpentine 
ftone,  the  Zoeblitz  ferpentine. 
a.  Black,     b.  Deep  green,     c.  Light  green.     </. 
Red.     e.  Bluifli  grey.    /.  White.     Thefe  co 
lours  are  all  mixed  together  in  the  ferpentine 
ftone  from  Zoeblitz,  but  the  green  is  the  moft 
predominant  colour. 

JB.  Porcelain 


C   «i    3 

.5.  Porcelain  earth  mixed  with  iron  j  terra  porcellanea* 

rr<i    •       • 

Ihis  is, 

A.  Diffufible  in  water. 

a.  Red,  from  Montmartre,  and  China.     The  wa-. 
ttr-clinkers  which  are  imported  from  certain 
places  in  Germany  feern  to  be  made  of  this 
kind. 
B.  Indurated. 

1.  Martial  foap  earth. 
a.  Red. 

2.  Martial  foap-rock, 

a.  Black. 

b.  Red. 

C.  The  telgften  of  the  Swedes  ;  lapis  ellarls. 

a.  Light  grey.     b.  Whitith  yellow,     c.  Dark 
grey.     d.  Dark  green. 

The  ferpentine  ftone  has  many  varieties ;  being 
found,  (i.)  Veined  or  fpotted  with  green  fteatites, 
(2.)  Red,  with  veins  of  afbeftos.  (3.)  Red,  green, 
yellow,  or  black  with  veins  or  fpots  of  white  calcare 
ous  fpar,  is  called potzevera.  The  black  is  called  nero 
dipraio  ;  the  green  verde  dl  Suza  ;  but  thefe  names  are 
not  retrained  to  this  fpecies.  (4.)  Veined  or  fpou 
ted  with  gypfum.  (5.)  Veined  or  fpotted  with  baro- 
felenite.  (6.)  Veined  or  fpotted  with  fhiftiis. — And, 
(7.)  With  veins  of  quartz,  feltfpar,  or  fhoerl,  (Kir* 
wan's  Mineralogy.) 

What  is  commonly  caNed  ferpentine  is  a  true  lapis  olla« 
rls ;  but  being  variegated  with  green,  yellowifh,  and 
brown  fpots,  like  the  fkin  of  feme  common  ferpents,  it 
is  called  by  that  name.  Great  quantities  of  this  ftone 
are  found  in  Italy  and  Switzerland,  where  it  is  often 
worked  into  the  fhape  of  difhes  and  other  vafes.  (Fa- 
Ironi.)  And  the  gabro  of  the  Italians  is  nothing  elfe 
but  a  kind  of  ferpentine,  ( Kirwan. ) 


§  2.  LTicaceous  Earths. 

Thefe  are  known  by  the  following  charade rs : 

1.  Their  texture  and  compofition   confift   of  thin 
flexible    particles,  divifible  into  plates  or  leaves, 
having  a  filming  furface. 

2.  Thefe  leaves  or  fcales  expofed  to  the   fire  lofe 
their  flexibility  and  become  brittle,  and  then  fe- 
parate  into  inner  leaves :    but  in  a  quick    and 
ftrong  fire,  they  curl  or  crumple,  which  is  a  ftep 
towards  fufion  ;  though  it  is  very  difficult  to  re 
duce  them  into  pure  glafs  by  themfelves  or  with 
out  addition. 

£.  They  melt  pretty  eafily  with  borax,  the  micro- 
cofmic  fait,  and  the  alkaline  fait :  and  may  by 
means  of  the  blow-pipe  be  brought  to  a  clear  glafs 
with  the  two  former  falts.  The  martial  mica  is, 
however,  more  fufible  than  the  uncoloured  ones : 
its  fpecific  gravity  is  3,000. 
A.  Colourlefs  or  pure  mica ;  daze,  glimmer,  orglift. 

1.  Of  large  parallel  plates  ;  Mufcovy  glafs.     This 
is  tranfparent  as  glafs  ;  found  in  Siberia  and  Elf- 
dalen  in  the  province  of  Wermeland. 

2.  Of  fmall  plates,  from  Silfverberget,  and  Runne- 
by,  in  the  province  of  Blekinge, 

3.  Of  fine  particles  like  chaff;  chaffy  mica.. 

4.  Of  twitted  plates;  crumpled  mica. 
J$.  Coloured  and  martial  glimmer.. 

1.  Brown,  femi-tranfparent.. 

2.  Of  fine  and  minute  fcales. 

a.  Brown.     1.  Deep  green,     g.  Light  greefta, 
d.  Black. 

5.  Twitted  or  crumpled  glimmer, 
a..  Light  green. 

4.  Chaffy  glimmer. 
a.  Black. 

5.  Chryftallifed  glimmer.- 

«.0f 


r  67  3 

a.  Of  concentrated  and  erect  fcales. 

b.  Of  hexagonal  horizontal  plated. 

The  tranfparent  Mufcovy  glafs  is  ufed  for  windows, 
and  upon  all  occasions  where  p^nes  of  ^la^'s  a^e  want 
ed.  Perhaps  it  might  alfo  be  ad/antageoufly  employ* 
cd  to  cover  houfes. 

The  twifted  or  crumpled  mica,  which  is  found  at 
Hardnl  in  Jemtland,  is  there  manufactured  into  kettles 
and  other  vdfels,  as  alfo  for  hearths  of  chimnies  :  and 
the  powder  which  falls  in  the  working  may  be  mixed 
with  the  common  fait  for  the  diftillation  of  the  muria 
tic  acid. 

§  3.   Afoejl'me  Eart&s. 

Thefe  are  only  yet  difcovered  in  an  indurated  ftate ; 
and  their  characters  are  as  follows  : 

j .  When  pure,  they  are  very  refractory  in  the  fire. 

2.  In  large  pieces  they  are  flexible. 

3.  They  have  dull  or  uneven  furfaces. 

4.  In  the  fire  they  become  more  brittle* 

5.  They  do  not  ftrike  fire  with  the  fteeL 

6.  They  are  not  attacked  by  acids. 

7.  They  are  eafily  brought  into  fufion  by  borax 
or  alkali. 

In  this  feftion  are  included  both  thofe  varieties 
xvhich  by  foffilogifts  have  been  mentioned  under  the 
names  of  amiantus  and  afbeftus,  and  have  often  been 
confounded  together. 

I.  Afbeftus,  which  is  compounded  of  foft  and  thin 

membranes  ;  amiantus  Walhrii. 

A.  Of  parallel  membranes  :   Corium,Ji<ve  caro  tnon» 
tana^  Mountain-leather. 

1.  l?ure.     a.  White. 

2.  Martial,     a.  Yello\vifli  brown. 

B*  Of  twifted  foft  membranes ;  mountain-cork* 
I.  Pure.     a.  White. 
2,.  Martial,     a.  Ycllowifh  brown. 

n.  or 


C     68    ] 

II.  Of  fine  and  flexible  fibres ;  or  earth    flax :  a 

tus  Wallerii. 
4.  With  parallel  fibres  :  By/us. 

1.  Pure  and  foft.     a.  Light  green,     b.  White. 

2.  A   little  martial,  and  more  brittle. 

a.  Greenifli,  from  Baftnas  Grufva,  at  Ryddar- 
hyttan    in    Weftmanland.     There  it  forms  the 
greateft  part  of  the  vein  out  of  which  the  copper 
ore  is  dug ;  a  great  part  of  it  is  confequently  melt 
ed  together  with  the  ore,  and  is  then  brought  to  a 
pure  femi-tranfparent  martial  flag  or  glafs. 
B.  Of  broken  and  recombined  fibres. 
I.  Martial,     a.  Light  green. 

Order  IV.  SILICEOUS  EARTHS. 

SILICEOUS  earth  is,  of  all  others,  the  mod  diffi 
cult  to  defcribe  and  to  diftingwifh  perfectly ;  however, 
it  may  be  known  by  the  following  characters,  which 
are  common  to  all  bodies  belonging  to  this  order, 
i.  In  its  indurated  ftate  it  is  hard,  if  not  in  regard 
to  the  whole,  yet  at  leaft  in  regard  to  each  par 
ticle  of  it,  in  a  degree  fufficient  to  flrike  fire  with 
fteel,  and  to  fcratch  it,  when  rubbed  againft  it, 
though  the  fteel  be  everfo  well  tempered. 
a.  When  pure,  and  free  from  heterogeneous  par 
ticles,  it  does  not  melt  by  itfelf,  neither  in  a  re-. 
verberatory  nor  in  a  blaft  furnace. 

3.  After  being  burnt,  it  does  not  fall  to  a  powder, 
neither  in  the  open  air  nor  in  water,  as  the  cal 
careous  earth  does,    but   becomes  only  a  little 
loofer  and  more  cracked  by  the  fire,  unlefs  it  has 
been  very  flowly,  and  by  degrees,  heated. 

4.  It  excites  no  eflfervefcence  with  acids. 

5.  In  the  fire  it  melts  eafieft  of  all  to  a  glafs  with  the 
fixed  alkaline  fait ;  and  hence  it  has  got  the  name 
of   vitrefcqnt,    though   this    name  is,    properly 

fpeaking, 


C    69    ] 

fpeaking,  lefs  applicable  to  this  order  than  to  a 
great  many  other  earths. 

To  the  above  we  may  add  the  following  properties  from 
Bergman. 

6.  It  is  not  foluble  in  any  of  the  known  acids,  the 
fluor-acid  only  excepted.     But, 

7.  It  may  be  diflblved  by  ihe  fixed  alkali,  both  in  the 
dry  and  wet  way. 

8.  If  the  fixed  alkali  is  only  half  the  weight  of  the 
filiceous   earth,    it    produces  a  diaphonous  and 
hard  glafs :  but  when  it  is  in  a  double  or  triple 
proportion,  then  the  glafs  deliquefces    of  itielf 
by  attracting  the  humidity  of  the  atmofphere.. 

9.  It  melts  eafily  with  borax  ;  but 

jo.  With  microcofmic  fait  it  is  more  difficult,  and 
requires  a  longer  time  to  melt. 

1 1.  This  earth  has  a  great  analogy  to  acids,  as  it  is 
perfectly  diflblved  in  that  wonderful  natural  hot- 
water  ipout  above  ninety  feet  high  at  Geyfer,  in 
Iceland,  where  by  cooling  it  forms  a  filiceous 
mafs. 

§  I.  Gems,  orpreciousjlones. 

I.  Diamond.     Adamas gemma.     See  DIAMOND. 

1.  Of  all  ftones,  it  is  the  hardeft. 

2.  Is  commonly  clear,  or  tranfparent ;  which  qua 
lity,  however,  may,  perhaps,  only  belong  to  its 
cryftals,  but  not  to  the  rock  itfelf  from  which 
they  have  their  origin. 

3.  Its  fpecific  gravity  is  neareft  3,500.     When 
brought  to  Europe  in  its  rough  Hate,  it  is  in  the 
form  either  of  round  pebbles  with  filming  fur- 
faces,  or  of  chryftals  of  an  ocloedral  form. 

a.  Colourlefs,  or  diaphonous,  or  the  diamond  pro 
perly  fo  called. 

But   it    alfo  retains  this  name   when  it  is 
tinged  fomewhat  red  or  yellow.     Being  rub 
bed, 


E    70    ] 

bed,  it  difcovers  feme  eleclrical  qualities,  and 
attracts  the  maftic. 

1.   Red ;      Ruby.      Adamas     ruler ;      Rublnus. — 
Which,  by  lapidaries  and  jewellers,  is,  in  re- 
gard  to  the  colour,  divided  into, 

1.  The  ruby  of  a  deep  red  colour  inclining  a 
little  to  purple, 

2.  Spinel),  of  a  dark  colour. 

3.  The  balafs,  pale  red,  inclining  to  violet. 
Thisisfuppofed  to  be  the  mother  of  the  rubies. 

4.  The  rubicell,  reddifh  yellow. 
However,  all  others  do  not  agree  in  the 

characters  of  thefe  ftones. 

II.  Sapphire.      Sapphyrus  gemma* 

It  is  tranfparent,  of  a  blue  colour  |  and  is  faid  to 
be  in  hardnefs  next  to  the  ruby,  or  diamond* 

III.  Topaz.     TTopai&htJ  gemma* 

a.  The  pale  yellow  topas  j    whkh  i§  nearly  un- 

coloured. 

I.  The  yellow  topaz. 
f.  Deep  yellow,  or  gold  coloured  topaz,  or  orien* 

tal  topaz. 

d-  Orange-coloured  topaz. 
e.  The  yellowifh  green  topaz  or  cljryfoKte. 
f.  The  yellowifh  green,  and  cloudy  topaz,   the 

chryfoprafe  (A) 

.  Bluifli 


(A)  In  the  Annals  of  Chemiftry,  Vol.  I.  we  have  the 
following  account  of  the  method  of  digging  for  the 
chryfoprafes,  and  of  the  earths  and  ftones  with  which 
it  is  accompanied. 

This  precious  ftone  is  found  in  certain  mountains  in 
Silefia,  which  feem  to  begin  thofe  of  Tradas,  extend 
ing  to  within  half  a  league  of  Glatz.  Thefe  moun 
tains  appear,  in  general,  to  confifl  of  a  number  of 
ftrafa,  horizontal  or  inclined,  compofed  chiefly  of  fub- 

ftancefr. 


C    7'    3 

g.  Bluifli  green  topaz,  or  the  beryl. 

This  varies  in  its  colours ;  and  is  called,  when 

1.  Of  a  fea-green  colour,  the  aqua-marina. 

2.  When  more  green,  the  beryl. 

IV.  Erne- 


fiances  containing  magnefia,  but  likewife  mixed  with 
calcareous,  argillaceous,  and  filiceous  earths.  The 
greaic.;-,  part  of  thefeconfilt  of  ferpentinej  mixed  with 
afbcllos  'inn  amianthus,  grey  argillaceous  earths, 
boles,  and  red  or  green  ochres,  (lone  marrow,  ftea- 
tites,  or  ibap-ftone,  and  talc.  In  thofe  mountains 
alfo  we  meet  with  quartz,  petrofilex,  opal,  and  chal 
cedony,  in  detached  fragments,  and  fomctimes  in  con 
tinued  veins.  We  alfo  difcover  in  them  veins  of  fand, 
of  the  nature  of  granite.  Sometimes  the  ferpentine 
\s  met  with  at  the  furface  ;  fometimes  at  the  depth  of 
20  or  30  feet.  The  ilone  marrow  feems  here  to  be 
produced  by  the  decomposition  of  a  very  milky  fpg- 
cies  of  opal  agate  named  dackolong ;  for  at  the  depth 
of  50  feet  and  upwards  the  veins  of  this  foapy  earth  af- 
fume  a  degree  of  folidity,  and  we  find  nothing  but  hard 
and  femitranfparent  chacholongs. 

The  abovementioned  (trata  are  croiled  by  a  great 
number  of  cracks  filled  with  green-coloured  earths 
and  (tones ;  but  thefe  frequently  do  not  contain  a  fingle 
true  chryfoprafus.  They  ai  e  fometimes  found  imme. 
diately  under  the  vegetable  mould,  or  at  the  depth  of 
fome  feet,  in  ihapelefs  mattes,  covered  with  a  heavy- 
clay,  and  fometimes  enveloped  by  an  uncluous  earth  of 
a  beautiful  green  colour,  which  it  derives  from  the 
calx  of  nickel.  In  other  places,  the  chryfoprafus  has 
been  found  in  uneven  laminae  of  feveral  yards  in 
length  and  breadth,  either  immediately  under  the 
mould,  or  in  the  upper  ftrata  of  ferpentine,  which  have 
kittle  folidity  ;  and  very  beautiful  ones  have  been  found 
at  the  depth  of  feven  or  eight  fathoms  5  and  fome  have 

been 


C    72    3 

IV.  Emerald.     Smaragdus  gemma. 

Its  chief  colour  is  green  and  tranfparent.  It 
is  the  fofteft  of  precious  ftones  and  when  heated 
it  is  phofphorefcent  like  the  fluors. 

V.  To 


been  met  with  in  grey  clay  at  the  depth  of  four  fa 
thoms.  In  fome  places  alfo  they  are  met  with  in 
a  kind  of  red  ochre,  which  is  attracted  by  the  magnet ; 
in  others  they  are  found  in  the  clefts  of  rocks.  The 
beautiful  green  chryfoprafus  is  found  moil  plentifully 
in  the  mountain  of  GlafTendorf.  In  another  moun 
tain  named  Kofemutz,  where  it  is  alfo  found,  the  pie 
ces  are  fo  porous,  and  fo  much  fpotted  with  white,  &c. 
that  fometimes  upwards  of  1000  of  them  have  not  af 
forded  one  large  enough  for  the  ufe  of  the  jewellers. 
The  defects  are  frequently  only  difcoverable  on  polifh- 
ing,  as  the  green  opal,  while  rough,  perfectly  refem- 
bles  the  chryfoprafus ;  but,  on  polifhing  the  ftones  in 
•which  it  is  contained,  it  is  detected  by  its  want  of  lu- 
ftre. 

The  quantity  in  which  thefe  ftones  are  found  is  not 
fufficient  to  afford  the  expences  of  regular  mining  ;  the 
mod  profitable  way,  therefore,  of  obtaining  them  is  by 
making  trenches  in  the  earth  from  four  to  fix  feat 
deep.  Almoft  all  the  mountain  of  Kofemutz,  how 
ever,  has  already  bee'n  examined  in  this  manner ;  fo 
that  they  now  dig  for  the  chryfoprafus  in  quarries  by 
uncovering  a  bank  of  earth  or  ftone,  and  deicending 
to  other  banks  by  fteps  in  the  open  air,  fo  as  to  throw 
the  rubbifh  back  from  bank  to  bank.  This  method, 
however,  cannot  be  continued  farther  than  24  or  30 
feet,  otherwife  the  produce  would  not  defray  the  ex- 
pence.  The  only  tools  employed  in  digging  for  the 
chryfoprafus  are  a  fpade  and  pick-ax ;  the  former  to 
remove  the  earth,  the  latter  to  detach  the  chryfoprafus 
itfelf  from  the  ftones  which  furround  it. 

Various 


I   n   ] 

V.  To  the  precious  ftones  belong  alfo  the  jacmths, 
or  hyaeinths ;  which  are  chryftals   harder  than 
quartz    cryftals,    tranfparent,  of  a  fine  reddifh- 
yellow  colour  when  in  their  full  luftre,  and  form 
ed 


Various  accounts  hava  been  given  of  the  component 
parts  of  this  precious  (lone.  Lehmann  thinks,  that 
the  colour  of  it  is  owing  to  fome  ferruginous  particles 
modified  in  a  particular  manner  :  but  the  experiments 
he  adduces  for  this  opinion  are  not  fatisfaclory.  Mr 
Sage  attributes  the  colour  to  cobalt  from  the  blue  co 
lour  it  imparts  to  glafs.  Mr  Achard  thinks  the  ftone 
contains  calx  of  copper  as  well  as  calx  of  iron  ;  be- 
caufe  a  part  of  the  metal  feparable  from  it  may  be  dif- 
folved  in  volatile  alkali.  The  following  are  the  expe 
riments  of  M.  Klapioth  upon  the  fubjeft. 

1.  On  heating  feveral  pieces  of  very  pure  chryfo- 
prafus  red4iot,  and  quenching  them  in  water,  the  co 
lour  was    changed   from  green  to  bluifh  grey  :  and, 
on  repeating  the  operation,  it  became  a  white  giey-. 
They  were  found  to  have  loft  in  weight  one  and  an  halt 
per  cent,  and  were  eafily  pulverable  in  a  glafs  mortar. 

2.  Three  hundred  grains  of  chryfoprafus  were  mix 
ed  with  double  its  weight  of  mild  mineral  alkali,  and 
the  mixture  heated  for  fome  hours  red  hot,  in  a  por 
celain   crucible.     The  mafs  was  then  powdered,  and 
digefted  in  diftilled  water.     By  filtration,  a  yellowifh 
grey  refiduum  was  obtained,  weighing  44  grains  ;  the 
filtered  liquor  was  limpid  and  colourlefs,  a  copious 
precipitate  bein-g  formed  with  muriatic  acid,  which  be 
ing  wafhed  and  dried  was  found  to  be  filiceous  earth. 

3.  The  44  grains  of  yellowifh  grey  refiduum  were 
digefted  in  a  retort,  with  552  grains  of  aqua  regia  ;  a 
groat  part  of  which  w  is  evaporated.     The  acid  which 
carrie  over  was  returned  into  the  retort,  and  filtered 
after  a  fecond  digeftion.     The  refiduum  was  a  very 

H  fine 


['    74    ] 

ed  in  prifms  pointed  at  both  ends :  thefc  points 
are  always  regular,  in  regard  to  the  number  of 
the  facets,  being  four  on  each  point ;  but  the  fa 
cets  feldom  tally  ;  the  fides  alfo  which  form  the 

main 


fine  white  filiceous  earth,  which,  after   being  waftied 
.dried,  and  heated  red  hot,  weighed  20  grains. 

4.  The  filtrated  folution  was  of  a  pale  green,  but 
on  fuperfaturation  with  volatile    alkali   immediately 
turned  of  a  blu  fh  colour,  precipitating  a  fmall  quan 
tity  of  brownifh  gelatinous  matter ;  which,  when  col 
lected,  twice  diftilled  with  nitrous  acid,  and  afterwards 
firongly  heated,  yielded  a  brown  calx  of  iron,  weigh 
ing  no  more  than  a  quarter  of  a  grain :  whence  our 
author  concludes,  that  iron  does  not  contribute  to  the 
colour  of  the  chryfoprafus,  as  we  know  many  colour- 
lefs  ftones  which    contain  as  great  a  quantity  of  that 
metal.     This  fmall  quantity  of  calx  was  left  after  dt- 
gefting    the  gelatinous  reiiduum.     On    precipitating 
the  foluble  parts,  they   appeared  to  coniift  of  alumi 
nous  earth,  in  an  exceffively  divided  Mate  ;  which  be 
ing  wafhed  and  dried,  weighed  half  a  grain. 

5.  To  find  whether  the  folution  contained  calcare 
ous  earth  or  not,  he  mixed  with  that,  fuperfaturated 
with  volatile  alkali,  a  faturated  folution  of  mild  mine 
ral  alkal',  which  precipitated  four  grains  and  an  half 
of  white  and  very  pure  calcareous  earth. 

6.  Nothing  more  was  precipitated  from  the  folution, 
either  by  acids  or  alkalies,  after  the  feparation  of  the 
calcareous  earth,  though  it  fall  retained  a  bluiih   co 
lour.     It  was  poured  into  a  retort,  and  evaporated  to 
drynefs  ;  the  reiiduum  was  of  a  yellowilh  colour,  which 
became  green  on  being   dilfolved   in  diftilled   water. 
Mild  mineral  alkali  threw  down  only  a  little  earth  of  a 
greeniih  white  colour  ;  which  being  re-diffblved  in  de- 
phlogifticated    nitrous    acid,    and   precipitated    with 

Pruffiaa 


[     75     3 

main  body,  or  column,  are  very  uncertain  in  re 
gard  both  to  their  number  and  fhape  ;  for  they 
are  found  of  four,  five,  fix,  feven,  and  fometimes 
of  eight,  fides ;  further  the  column  or  prifm 

is 


Pruflian  alkali,  the  liquor  yielded  17  grains  of  a  fea- 
green  powder.  This  precipitate,  in  our  author's  opi 
nion,  is  the  colouring  principle  of  the  chryfoprafus  ; 
and  this  principle  heafterwards  found  to  be  calx  cf 
nickel. 

7.  Our  author  likewife  attempted  to  analyfe  the  chry 
foprafus  in  the  moid  way  by  concentrated  viziblic  acid ; 
in  which  procefs  his  chief  view  was  to  difcover  whe 
ther  the  ilone  contained  any  volatile  particles  or  not. 
On  an  ounce  of  crude  chryfoprafus,  therefore,  when 
put  into  a  retort,  he  poured  an  equal  quantity  of  recli- 
fied^vitriolic  acid,  and  two  parts  of  diftilled  water.  Af 
ter  the  latter  had  pafied  over  into  the  receiver,  the  fire 
was  increafed  to  force  over  the  fuperabundant  acid  } 
a  part  arofe  in  white  vapours,  and  fome  fell  into  the 
receiver  with  an  hiding  noife.  Boiling  water,  which 
had  been  diftilled,  was  then  poured  upon  the  refi- 
duum,  and  the  folution  filtered.  The  powdered  chry 
foprafus  left  on  the  filter  had  not  been  perfectly  dilTol- 
ved,  and,  in  general,  had  .undergone  but  little  altera 
tion,  fo  that  he  could  not  by  this  method  determine 
the  component  parts.  M.  Achard,  however,  was 
more  fuccefsful,  and  by  a  fimilar  method  determined 
the  component;  parts  of  this  gem  to  be  five  grains  of  an 
earth,  which,  diftilled  with  vitriolic  acid,  became  vo 
latile  ;  eight  grains  of  calcareous  earth,  fix  grains  of 
magnefia,  two  grains  of  calx  of  iron,  three  grains  cf 
calx  of  copper,  and  456  of  filiceous  earth. 

M.  Klaproth  never  met  with  any  volatile  earth  or 
magnefia  in  his  experiments  on  this  gem  ;  and  there 
fore  concludes,  that  the  chryfoprafus  ufed  by  him  had 
H  2  been 


is  in  feme  alfo  fo  comprefTed,  as  almoft  to  re- 
iemble  the  face  of  a  fpherical  facetted  garnet. 

Mr  Cronftedt  fays,  he  got  foma  jacinths  of  a 
quadrangular  figure,  which  did  not  melt  in  the 
fire,  but  only  became  colourlefs. 

VI.  The 


been  eflentially  different  from  that  made  ufe  of  by 
M.  Achard  ;  and  he  feems  not  to  give  credit  to  the 
account  of  any  copper  being  found  in  it. 

8.  One  part  of  crude  chryfoprafus,  well  powdered 
and  wafhed  with  two  parts  of  mild  vegetable  alkali, 
yielded   a  violet-coloured  glafs,  which  in  the  atmof- 
phere  ran  into  a  brownilli-ccloured  liquor. 

9.  Five  parts  of  the  gem,  with  four  of  mild  alkali, 
gave  a  beautiful  violet-coloured  glafs  after  being  two 
hours  in  fufion. 

io»  Equal  parts  of  crude  chryfoprafus  and  mild  mi 
neral  alkali,  yielded  a  tranfparent  glafs  in  thin  laminae, 
cf  a  brown  colour,  refembling  that  ©f  the  tourmalin, 
the  furface  being  marked  with  fine  reticulated  veins  ; 
which  veins  arofe  from  fmall  grains  of  very  fine  redu 
ced  nickel  placed  in  lines  againft  one  another. 

1 1 .  Equal  parts  of  crude  chryfoprafus  and  calcined 
borax,  gave  a  clear,  tranfparent,  and  brown  glafs,  re* 
fembling  the  fmoky  topaz. 

12.  Equal  parts  of  chryfoprafus,  extracled  by  vitri 
olic  acid  and  calcined  borax,  yielded  a  fimilar  glafs  of 
a  clear  brown  colour;  "  which  proves    (fays  our  au 
thor),  that  the   vitriolic   acid  was  incapable  of  per 
fectly  analyfmg  the  chryfoprafus,  though  I  had  ufed  a 
double  portion  of  the  earth." 

13.  Eighty  grains  of  prepared  filiceous  earth,  fixty 
grains  of  mild  fixed  alkali,  with  the  three  grains  of 
calx  of  nickel  procured  from  the  chryfoprafus,  yielded 
a  beautiful,  clear,  and  violet-coloured  glafs. 

14..  Qn  fubftituting  three  grains  of  calx  produced 

from 


C     77     3 

VI.  The  amethyft  is  a  gem  of  a  violet  colour,-  with 
great  brilliancy,  and  as  hard  as  the  bed  kind  of 
rubies  or  fapphtres,  frcm  which  it  only  differs 
by  its  colour.  This  is  called  the  oriental  ame- 

tlyjl; 


from  an  ore  of  nickel,  a  glafs  was  produced  exactly 
like  the  former. 

15.  Sixty  grains  of  prepared  filiceous  earth  and  caV 
cined  borax,  with  three  grains  of  calx  of  nickel  from 
the  chryfoprafus,  yielded  a  tranfparent  glafs  of  a  clear 
brown  colour. 

1 6.  Sixty  grains  of  prepared  filiceous  earth  and  vi 
trified  phoiphoric  acid,  with  three  grains   of  calx  of 
nickel  from  the  chryfoprafus,  gave  a  glafs  of  the  co 
lour  of  honey. 

17.  Thus  the  attempts  of  M.  Klaproth  to  recompofe 
the  chryfoprafus   proved  abortive.     From  his  experi 
ments,  however,  he  deduces  the  following  conclufions  : 
i.  The  blue  colour   obfervable  in  the   glafs  produced 
by  fusing  the  chryfoprafus  with  vegetable  alkali,  ariits- 
entirely  from  the  nickel  contained  in  the  gem  :  and  the 
experiment  (hows  that  the  calx  of  nickel,  when  puri 
fied  as  much  as  poffihle,  has  the  furpriiing  property. 
of  tinging  glafs  frits  prepared  with  vegetable  alkali  of 
a. blue  colour,.     "  But  (fays  he)  why  was  not  this  co 
lour   alfo   obtained  with  foda  ?  and  what  is  the  caufe 
of  a  difference  fo  little  to  be  expected?"   2.  By  thefe 
experiments    the  fuppofition  of  M.    Sage  is  refuted,, 
that  the1' metallic  matter  which  colours  the  chryfopra 
fus  is  cobalt :   "  many   metallic  fubftances  befides  co- 
foalti  it  is  well  known,  give  by  certain  procefTes  ;i  blue 
glafs;  thus  cobalt  gives  a  blue  colour  to  cornbma'.ions 
ef  the  mineral  alkali  with  phofphoric  acid,  to  mineral 
alkali   itlclf,  to   potafh,   and  to  borax.     The  a^i  \  of 
tiingften  (falfelyfo  calbd)  alfo  nives  a  blue  col-- 

frits  made  with  phofphoric  ialts,  but 'not  to  tl-ioic;  m  i'Jcr. 
H  3  with. 


C     75     J 

thy/I  s  and  is  very  rare:  when  it  inclines  to  the 
purple,  or  rofy  colour,  it  is  more  efteemed  than 
when  it  is  nearer  to  the  blue. 

Thefe 


with  borax  ;  the  calx  of  nickel  gives  a  blue  colour  on 
ly  to  frits  made  with  potafh,  brown  to  thofe  with  mi 
neral  alkali  and  borax,  and  yellow,  like  honey,  to 
combinations  of  phofphoric  acid  with  mineral  alkali.'* 
3.  As  the  chryfoprafus  gives  a  brown  colour  with  bo 
rax,  and  the  foluiion  of  this  (tone  in  muriatic  acid 
gives  no  figns  of  cobalt  diflblved  in  the  fame  acid  ;  this 
fhows  that  there  is  no  cobalt  in  the  ftone.  Mr  Sage, 
indeed,  pretends,  that  he  has  obtained  a  blue  glafs 
from  the  chryfoprafus  and  borax  ;  but  this  is  contra 
dicted  by  experience.  4.  The  mineralogical  character 
of  the  chryfoprafus,  therefore,  is  a  quartz  coloured 
green  by  nickel.  Three  hundred  grains  of  it  contain 
2887  of  filiceous  earth  calcined  to  redaefs,  one  quar 
ter  of  a  grain  of  pure  aluminous  earth,  two  grains 
and  an  half  of  calcareous  earth  calcined  to  rednefs, 
three  grains  of  calx  of  nickel,  and  one  quarter  of  a  grain 
of  calx  of  iron.  All  thefe  were  extracted  in  the  expe 
riments  ;  and  there  were  befides  five  grains  and  an  half 
of  wafte. 

Our  author  mentions,  that  in  the  collections  of  chry 
foprafus  which  have  been  brought  to  him,,  he  has  con- 
ftantly  observed  green  opal,  in  bits  of  vein  from  half 
an  inch  to  an  inch,  and  fixed  in  its  borders  :  the  red- 
difh,  yellow,  and  white  opals,  on  the  contrary,  are  ge 
nerally  met  with  on  a  green  or  brownifh  petrofilex. 
But  the  white  opal,  which,  as  well  as  the  green,  is 
found  in  pieces  of  the  nature  of  matrix,  differs  from 
the  true  opal,  approaching  the  chalcedony  and  the 
epaque  milky  quartzes.  This  kind  of  tranfparent 
opal,  radiated  with  a  whitifh  blue,  contains  the  fol- 
fcwjng  ingredients  in  its  competition ;  Siliceous  earth, 

237 


C    79    3 

Thefe  amethyfts  have  the  fame  figure,  hard- 
Befs,  fpecific  gravity,  and  other  qualities,  as  the 
beft  fapphires  or  rubies;  and  come  from  the  fame 
places,  particularly  from  Perfu,  Arabia,  Arme 
nia,  and  the  Weil  Indies. 

The  arjethyfts  called  occidental,  are  of  the 
fame  nature  as  rock  cryllals,  and  have  the  fame 
gradations,  viz.  of  a  violet  inclining  to  the 
purple  or  rofy  colour,  or  inclining  to  the  blue  ; 
very  often  they  are  femi-tranfparent,  without 
any  colour  in  one  end,  and  violet  towards  the 
other.  The  bed  are  found  in  the  Vic  moun 
tains  of  Catalonia  in  Spain,  and  at  Wiefenthal 
in  Saxony,  as  well  as  in  Bohemia  in  Germany, 
in  Italy,  and  in  the  province  of  Auvergne  in 
France. 

Cryftals  within  the  geodes,  or  hollow  agathe- 
balls,  are  very  often  found  of  an  amefhyit  co 
lour,  and  fome  are  very  tine. 

What  we  call  amethyjl  root,  or  mother  of  ame* 
tbyjl,  is  but  a  fparry  fluor,  of  which  there  are 
plenty  in  Derbyihire  :  many  fine  ornamental  pie 
ces  are  made  of  this  fubftance  in  different  forms 
and  fhapes,  Thefe  fpars  are  found  in  infulated 
maffes,  ibmetimes  pretty  large  ;  but  never  in  the 
form  of  large  rocks. 

VII>  The  garnet,  (Granatus.)  This  ftcne,  when 
tranfparent  and  of  a  fine  colour,  is  reckoned 
among  the  gems :  but  it  varies  more  than  any, 
both  in  the  form  of  its  cryftals  and  in  its  colour, 

fome 


237  grains;  aluminous  earth,  a  quarter  of  a  grain; 
calx  of  iron,  a  quarter  of  a  grain — in  all,  23 yt  grains. 
In  240  grains  were  two  and  an  half  of  wafte.  The 
colour  of  this  ftone,  as  well  at  the  chryfoprafus,  in  our 
author's  opinion,  is  derived  from  nickel* 


C    80    J 

fome  being  of  a  deep  and  dark  red,  fome  yellow- 
ijfh  and  purplifh,  and  fome  brown,  blackifh*  and 
quite  opaque.  In  general,  their  luftre  is  lefs  than 
that  of  oiher  gems,  as  well  as  their  hardnefs, 
which  yields  to  the  file,  although  they  may  ftrike 
fire  with  fteel.  But  as  to  rheir  form,  thefe  cry- 
ftals  take  almoft  all  forts  of  figures,  as  the  rhom- 
boidal,  tetradecaedral,  £c.  and  fome  ar.e  of  an 
irregular  form. 

Their  colour  proceeds  from  the  iron  which  en 
ters  into  their  compofition  ;  and,  according  to 
M.  de  Sauflure,  even  the  fined  oriental  garnets 
attracl  the  magnetic  needle  at  a  fmall  diftance. 

The  Syrian  garnet  is  the  fineft  and  beft  efteem- 
ed.  It  is  of  a  fine  red,  inclining  to  the  purple 
colour,  very  diaphanous,  but  lefs  brilliant  than 
the  oriental  amethyft.  It  feems  to  be  the  ame- 
thyjlizontas  of  Pliny  :  the  Italians  call  it  rublno  di 
rocca9  and  is  found  in  Syria,  Calcutta,  Cananor, 
Camboya,  and  Ethiopia. 

The  fine  garnet  of  a  red  inclining  to  a  yellow 
colour,.,  is  the  f-;ranus  of  the  ancients,,  the  *uer- 
ntdlle  of  the  Fiench,  and  the  giaclnto  guarnacino 
of  the  Italians.  Its  name  is  taken  from  So- 
riant  or  Surian9.a.  capital  town  of  Pegu,  from 
whence  thetc  gems  are  brought :  when  they 
have  a  browniili  taint,  they  are  then  called  hy 
acinths. 

The  occidental  garnet  is  of  a  deep  and  dark 
red,  and  its  hardnefs  is  leffer.  However,,  fome 
very  fine  hard  garnets  are  found  in  Bohemia. — 
Garnets  are  alfo  found  in  Hungary,  at  Pyrna  in 
Silefia,  at  S.  Sapho  in  the  canton  of  B^rne,  in 
Spain,  and  rn  Nonvay. 

The  garnet  melts  in  the  focuis  of  a  good  burn 
ing  gbfs  into  a  brown  mafs,  which  is  attracted 
by  the  loadstone  ;  and  this  ftiows  that  iron  enters 
e.cnfidcrabiy  into  its  ccmpofition,. 

Some 


t  •'  ] 

Some  garnets  are  found,  which  contain  a  little 
gold.     Thofe  called  ztngraupen  by  the  Germans 
contain  tin, 
VIII.  Tourmalin  ;  Lapis  eleflricits. 

This  is  a  kind  of  hard  ftone,  lately  brought 
into  notice  by  its  electrical  properties.  See 
TOURMALIN. 

j.  Its  form  is  a  prifm  of  nine  fides  of  different 
breadths,  moftly  truncated,  and  feldom  termi 
nating  in  a  pyramid  at  each  end,  which  is  ei 
ther  compofed  of  three  pentagons,  or  of  nine 
triangles. 

2.  When  heated  in  the  fire,  it  gives  figns  of  con 
trary  electricity  on  the  two  oppofitc-  ends  of  their 
prifmatic  form.    But  many  of  thefe  ftones  are  not 
in  the  leaft  electric.     However,  on  being  rubbed, 
they  become  electric  in  their  fides,  like  other  dia 
phanous  gems. 

3.  It  is  as  hard  almoft  as  the  topaz,  and  ftrikes  fire 
\viih  fteeL 

4.  It  melts  by  itfelf  in  a  flrong  fire,  though  with 
difficulty. 

5.  With  the  microcofmic  fak  it  welts  perfe«ftly  j 
but  only  in  part  with  borax. 

6.  With  mineral  alkali  it  is   divided  into  a  kind  of 
powder. 

7.  The  three  mineral  acids  diflblve  it  when  firftrc« 
duced  to  a  powder. 

8.  It    bears  a  greater    fimilarity    to  fchoerl  than 
to  any   other    ftone :    but   its   component  parts 
fhow  that  it  may  be  ranged  with  propriety  in 
this  place,  along  with  other  precious  ftones  :  as 
the  argillaceous  earth  is  alfo  the  moft  prevalent 
in  its  compofition. 

a.  The  oriental  tourmalines  are  found  in  the 
ifland  of  Ceylon.  They  are  tranfparent,  of  a 
dark  brown  yellow ;  and  their  fpecific  gravity- 
is  from  3062  to  3295. 

t.  Froia 


[      82      ] 

£.  From  Brafil.  Tranfparent.  Thefe  are  green 
for  the  mod  part ;  but  there  are  alfo  fome  red, 
blue,  and  yellow :  their  fpecific  gravity  is  from 
3075  to  3180. 

c.  From  Tyrol.     Of  fo  dark  a  green  as  to  ap 
pear  opaque.     Their  fpeciiic  gravity  is  about 
3050.     Thefe  are  found  in   beds  of  ftcatites 
and  lapis-ollaris,  among  the  micaceous  veins, 
talcs,  and  hornblende  of  Schneeberg,  Jurzagl, 
and  Zillerthal,  in  the  mountains  of  Tyrol. 
</.  From  the  mountains  of  Old  Caftile  in  Spain. 
Thefe  are  tranfparent,  and  have  the  fame  pro 
perties  as  the  preceding  ones. 
The  opal,  Opalm  ;  the  girafok  of  the  Italians.—- 
This  is  the  moft  beautiful  of  all  the  Flint  kind, 
owing  to  the  changeable  appearance  of  its  co 
lours  by  reflexion  and  refraction,  and  mud  there 
fore  be  ddcribed  under  both  thefe  circumftances. 
The  opal  of  Nonnius,  the  Sangenon  of  the  Indi 
ans.     This  appears  olive -coloured  by  reflection, 
and  feems  then  to  be  opaque  ;  but  when  held  a- 
gamft  the  light,  is  found  tranfparent  and  of  a  fine 
ruby  red  colour. 

There  is,  however,  another  of  the  fame  kind 
in  Sweden,  which  by  reflection  appears  rather 
brown ;  but  by  refraction  it  is  red,  with  violet 
veins. 

The  white  opal.  Its  ground  is  white,  of  a  glafs- 
like  complexion,  from  whence  are  thrown  out 
green,  yellow,  purple,  and  bluifh  rays  ;  but  it  is 
of  a  reddifh  or  rather  flame-colour  when  held  a-» 
gainft  the  light. 

a.  Of  many  colours  ;  the  oriental  opal. 

b.  Of  a  milky  colour. 

c.  Bluifh,  and  femi-tranfparent.     This  is  not 
fo  much  valued  as  thofe  which  are  more  o* 
paque,  becaufe  it  is  eafier  to  be  imitated  by  art. 


C     *3     ] 

§   2.     Of  Quartz. 

This  (lone  is  very  common  in  Europe,  and  e&fier  to 
be  known  than  defcribed.  It  is  diitinguiftied  from 
the  other  kinds  of  the  filiceous  order  by  the  following 
qualities  : 

1.  That  it  is  moft  generally  cracked  throughout, 
even  in  the  rock  itf-lf ;  whereby, 

2.  As  well  as  by  its  nature,  it  breaks  irregularly, 
and  into  fharp  fragments. 

3.  That  it  cannot  eafily  be  made  red-hot  without 
cracking  ftill  more. 

4.  It  never  decays  in  the  air. 

5.  Melted    with   pot-afhes,    it  gives    a  more  folid 
and  fixed  glafs  than  any  other  of  the  filiceous  or 
der. 

6.  When  there  has  been  no  interruption  *n  its  na 
tural  accretion,  its  fubftance  always  cryftallifes 
into  hexagonal  prifms  pointed  at  one  or  both 
ends. 

7-  It  occurs  in  clefts,  figures,  and  fmall  veins  in 
rocks.  It  very  feldom  forms  large  veins,  and  ftill 
feldomer  whole  mountains,  without  being  mixed 
with  heterogeneous  fubftances. 

According  to  Mr  Kirwan,  quartz  neither  lofes 
its  hardnefs  nor  its   weight  by  calcination.      Its 
texture  is  lamellar.     Thefe  ftones  are  in  general 
the   pureft   of  the    filiceous  kind,    though  mod 
contain  a  flight  mixture  of  other  earths  ;  the  moft 
obvious  diftincHon  among  them  arifes  from  their 
*•  tranfparency  or  opacity. 
Quartz  is  found, 
(i.)  Pure. 

A.  Solid,  of  no  vifible  particles,  with  a  gloffy  fur- 
fkce.  Fat  Quartz. 

a.  Uncoloured  and  clear.  This  has  no  cryftallized 
form,  but  is  neverthelefs  as  clear  as  quartz  cry- 
ilals  of  the  beft  water. 

b.  White, 


C    84    ] 

b.  White,  the  common  fat  quartz. 
<?,  Blue. 
d.  Violet. 

B,  Grained. 

a.  White.     I.  Pale  green. 

C.  Sparry  quartz. 

This  is  the  fcarceft;  and  ought  not  to  be  con 
founded   with    the    white    felt-fpar,    being  of  a 
-imoother  appearance,  and  breaking  into  larger 
and  more  irregular  planes. 
a.  Whitifh  yellow,     b.  White. 
Z>.    Cryftallifed  quartz.       Rock  cryftal.      Quartz 
cryftal. 

1.  Opaque,  or  femi-tranfparent. 

a.  White,  or  of  a  milk  colour. 

b.  Red,  or  of  %  carnelian  colour. 

c.  Black. 

2.  clear. 

a.  Blackifh  brown,  fmokey  topaz,  or  raunch  topaz  of 
the  Germans. 

b.  Yellow ;  found  in  Bohemia,  and  fold  inftead 
of  topazes. 

c .  Violet ;  the  amethyft  from  Saxony,  Bohemia, 
and  Dammemore  in  Upland  (B.) 


(B.)  The  moft  tranfparent  are  called  falfe  diamonds, 
Briftol,  Kerry  Jlones,  and  Alsngon  dlamsnds,  &c.  The 
coloured  tranfparent  cryftals  derive  their  tinge  gene 
rally,  from  metallic  calces,  though  in  exceeding  fmall 
portions:  they  all  lofe  their  colours  when  ftrongly 
heated.  Thefe  are  what  we  call  falfe  gems,  viz. 

The  red,  from  Oran  in  Barbary,/2z^  rubies. 

The  yellow,  from  Saxony,/^  topazes, 

The  green,  from  Dauphiny,  (very  rare)  fclfe  emeralds, 
or  frnfes. 
.   The  violet,  from  Vil  in  Catalonia,  falff  amethyfts. 

'The  blue,  from  Puv  in  Valay,  Franc s,  falfe fapphircs. 


d.  Uncoloured  :  rock  cryftal,  properly  fo  called. 
When  thefe  coloured  cryftals  are   not   clear, 
they  are  called^«/>  /    for  inftance,   topaz-flufs , 
ameihyjl  fufs )  &c.  (c-) 
(2.  Impure  quartz. 

A.  Mixed  with  iron,   in  form  of  a  black  calx. — 
This  is  of  a  glofly  texture,  and  contains  a  great 
quantity  of  iron. 

B.  Mixed  with  copper  in  form  of  a  red  calx. 
a.  Red. 


There  are  alfo  opal,  or  rainbow  cryjlals^  fome  of  which 
make  a  very  fine  appearance  ;  the  various  colours  of 
which  are  thrown  out  in  zones  acrofs  the  furface,  tho* 
they  never  fliine  like  the  oriental  opal. 

( c  \  M.  Fourcroy  makes  a  remarkable  difference  be 
tween  the  cryftals  and  the  quart/,  by  affirming  that 
the  former  are  unalterable  in  the  fire,  in  which  they 
never  lofe  their  hardnefs,  tranfparency,  nor  colour  ; 
whilft  the  quartz  lofes  the  fame  qualities,  and  is  re 
duced  by  it  to  a  white  and  opaque  earth.  He  claffes 
the  rock  cryftals, 

i  ft,  According  to  their  form,  viz.  i.  Infulated-hexa- 
gonal-cryftals,  ending  in  two  pyramids  of  fix  faces, 
which  have  a  double  refraction  or  fhow  two  images  of 
the  fime  object  when  looked  through.  2.  Hexagonal 
cryftals  united,  having  one  or  two  points.  3.  Tetrasd- 
ral,  dodecsedral,  flated  cryfta'is;  and  which  though 
hexagonal  have  neverthelefs  their  planes  irregular.  4. 
Cryilals  in  large  maiTes,  from  the  iiiand  of  Madagaf- 
car,  which  have  a  fimple  refraction. 

2dly,  As  to  the  colour,  they  are  either  diaphonous, 
reddiin,  fmokey,  or  blackifh. 

3dly,  As  to  accidental   changes,  fome  are  hollow, 

fome  contain  'water  within  one  or  more  cavities  :  fome 

are  cafed,   viz.  one   withjn  the  other  :  fome  are  of  a 

round  form,  as  the  pebble  vf  the  Rhine;  fome  have  a 

I  cruft 


§  3«     Of  Flints. 

THE  flint  (Szlex  pyromachus,  Lapis  corneus,  or  the 
bornjlim  of  the  Germans)  forms  a  kind  of  interme 
diate  fubftance  between  quartz  andjafper;  both  which, 
however,  it  fo  nearly  refembles,  that  it  is  not  eafy  to 
point  out  fuch  characters  as  fhall  readily  diftinguih  it 
from  them.  We  can  only,  therefore,  fpeak  of  its  pro 
perties  comparatively. 

1.  It  is  more  uniformly  folid,   and  not  fo  much 
cracked  in  the  mafs  as  the  quartz ;  and, 

2.  It  is  more  pellucid  than  the  jafper. 

3.  It  bears  being  expofed  to  the  air  without  decay 
ing  better  than  the  jafper,  but  not  fo  well  as  the 
quartz. 

4.  It  is  better  for  making  of  glafs  than  the  jafper, 
but' is  not  quite  fo  good  as  quartz  for  that  pur- 
pofe. 

5.  Whenever  there  has  been  an  opportunity  in  this 
matter  of  its  fhooting  into  cryftals,  quartz  cry 
ftals  are  always  found  in  it ;  juft  as  if  the  quartz 
made  one  of  its  conftituent  parts,  and  had  in  cer 
tain  circumftances  been  fqueezed  out  of  it ;  this 
is  to  be  feen  m  every  hollow  flint  and  its  clefts, 
which  are  always  filled  up  with  quartz. 

3).  It  often  fhows  moft  evident  marks  of  having  been 
originally  in  a  foft  and  flimy  tough  ftate  like  glue 
or  jelly. 


cruft  of  metallic  calces,  or  of  a  pyrites  :  Ibme  are  of  a 
.geodical  form,  viz,  cryftallifed  in  the  infide  of  a  cavity ; 
fome  feem  to  contain  amianthe,  or  afbeftus,  and  others 
contain  (hirls. 

The  fame  author  reckons  among  cryftals,  the  orien 
tal  topaz,  the  hyacinth,  the  oriental  fapphire,  and  th« 
amethyft.  Mr  Daubenton  had  always  looked  on  this 
laft  as  a  quartzous  cryftal. 


C    87    ] 

The  feveral  varieties  of  this  fpecies  have  ob 
tained  more  diftincl:  names  with  refpecT:  to  their 
colours  than  from  any  real  difference  in  their 
fubftance ;  but  thefe  are  ft  ill  neceflary  to  be  re 
tained,  as  the  only  names  ufed  by  jewellers  and 
others,  who  know  how  to  value  them  accord 
ingly. 
I.  Jade.  Lapis  nephriticus.  jfajpachates* 

The  true  lapis  nephriticus  feems  to  belong  to 
this  filiceous  order,  as  it  gives  fire  with  fteel, 
and  is  femi-pellucid  like  flint ;  it  does  not  har 
den  in  fire,  but  melts  by  the  folar  heat  in  the 
focus  of  a  burning  lens  into  a  tranfpareiat  green 
glafs  with  fome  bubbles.  That  called  by  the 
name  of  circoncifion  Jlone^  which  comes  from  the 
Amazon  river,  melts  eafier,  in  the  fame  folar 
fire,  into  a  brown  opaque  glafs,  which  is  far  lefs 
hard  than  the  ftone  itfelf.  (Macquer.) 

This  ftone  is  fuperior  in  hardnefs  to  quartz^ 
though  from  its  uncluofity  to  the  touch,  one 
would  fufpect  it  to  contain  a  large  portion  of 
argillaceous  earth,  or  rather  of  magnefian  earth, 
as  Mr  Kirwan  feems  to  fufpect. 

Its    fpecific    gravity  is  from    2,970    to   3,389 

It  is  of  a  granular  texture,  of  a  greafy  look,  and 
exceedingly  hard:  is  fcarcely  foluble  in  acids, 
at  leaft  without  particular  management,  and  is 
infufible  in  the  fire.  M.  Saufiure  feems  to  have 
extracted  iron  from  it. 

a.  It  is  fometimes  of  a  whitilh  milky  colour,  from 
China :  but  moftly 

If.    Of  a  greenilh,  or 

c.  Deep-green  colour,  from  America. 

d.  Grey,  yellowifK,  and  olive  colour :  thefe  are  the 
vulgar  lapis  nephriticus,   they  being  fuppofed  to 
cure  the  nephritic  pains  by  their  external  appli 
cation  to  the  loins. 

I*  The 


L     83     J 

The  femi-pellucidity,  hardnefs,  and  fpecific  gra 
vity,  are  the  characters  by  which  the  lapis  ne- 
phriticus  may  be  diftinguilhed  from  other  ftones. 

II.  Cat's   eye  ;    Pfeudopalus.     The    fun-ftone   of  the 
Turks,  called  gunechc. 

This  ftone  is  opaque,  and  reflects  green  and  yel- 
lowiih  rays  from  its  furface  :  it  is  found  in  Sibe 
ria.  It  is  very  hard  and  femi-tranfparent,  and 
has  different  points,  from  which  light  is  reflected 
with  a  kind  of  yellow-brown  radiation,  fomewhat 
fimilar  to  the  eyes  of  cats,  from  whence  it  had 
its  name.  Jewellers  do  not  fail  to  cut  them 
round  to  the  gre.ateft  advantage.  The  beft  of 
thefe  ftones  are  very  fcarce.  One  of  thefe  of  one 
inch  diameter  was  in  the  cabinet  of  the  grand 
duke  of  Tuicany. 

III.  Hydrophanesy  or  Qculus  Mundl  ;  alfo  called  Lapis 
mutabilis. 

The  principal  property  which  diftinguifhes  this 
from  all  other  ftones,  is  that  it  becomes 
tranfparent  by  mere  infufion  in  any  aqueous 
fluid  '3  but  it  gradually  relumes  its  opacity  when 
dry. 

IV.  The  onyx.     Onyx  camehuja.     Memphites.     It  is 
found  of  two  forts. 

a.  Nail-coloured  onyx,  having  pale  fiefh- coloured 

and  white  lines. 
I}.  With    black    and  white  lines.     The  oriental 

onyx. 

V.  The  chalcedony,  or  white  agate,  is  a  flint  of  a  white 

colour,  like  milk  diluted  with  water,  more  or  lefs 
epaque  :  it  has  veins,  circles,  and  round  fpots. 
It  is  faid  to  oe  fofter  t;han  the  onyx,  but  much 
harder  than  thofe  agates  which  are  fometimes 
found  of  the  fame  colour. 

a.  The  white  opaque  Chalcedony,  or  caholong, 
from  the  Buckharifh  Calmucks.  This  was  firit 
made  known  by  one  Renez,  a  Swedifh  officer, 

who 


C    S9    ] 

who  for  feveral  years  had  been  in  the  country. 
The  inhabitants  find  this  flint  on  the  banks  of 
their  rivers  and  work  idols  and  domeftic  vef- 
fels  out  of  it. 

b.  Of  white    and  femi-tranfparent  ftrata;  from 
Ceylon. 

c.  Bluifh  grey  :  from  Ceylon  and  Siberia. 

VI.  The  carnelian.      Carniolus. 

Is  of  a  brownilh  red  colour,  and  often  entirely 
brown.  Its  name  is  originally  derived  from  its 
refemblance  to  flefh,  or  to  water  mixed  with 
blood. 

a.  Red. 

b.  Yellowilh  brown,  looks  like  yellow  amber.     It 
is  faid  not  to  be  fo  hard  as  the  chalcedony. 

VII.  The  fardonyx. 

This  is  a  mixture  of  the  chalcedony  and  carnelian, 
fometimes  ftratumwife,  and  fometimes  confufedly 
blended  and  mixed  together. 

a.  Stripped  with  white  and  red  ftrata  ;  this  ferves 
as  well  cut  in  cameo  as  the  onyx. 

b.  White,    with   red  dendritical    figures.     This 
very  much  refembles  that  agate  which  is  called 
the  mocha  Jlone ;  but  with  this  difference,  that 
the  figures  are  of  a  red  colour  in  this,  infteacl 
of  black,  as  in  that  agate. 

Between  the  onyx,  carnelian,  chalcedony, 
fardonyx,  and  agate,  there  feems  to  be  no  real 
difference,  except  fome  inexplicable  degrees  of 
hardnefs. 

VIII.  The  agate  ;  debates. 

This  name  is  given  to  flints  that  are  variega 
ted  with  different  colours,  promifcuouily  blended 
together  :  and  they  are  efteemed  in  proportion  to 
their  mixture  of  colours,  their  beauty,  and  ele-- 
gance.  Hence  alfo  they  have  obtained  variety 
of  names,  moftly  Greek,  as  if  the  bufmefs.of  the 
lapidary  in  cutting  of  them,  and  admiring  their 
I  3 


C    90   J 

feveral  beauties  and  figures,had  been  derived  from 

that  nation  alone  *. 

a.  Brown  opaque  agate,  with  black  veins,  and 

dendritical  figures  :  the  Egyptian  pebbles. 
£.  Of  a    Chalcedony  colour  j    debates    cbalcedoni- 

fans. 

c.  Semi-tranfparent,     with  lines    of  a   blackifh 
brown  colour,  and  dendritical  figures  ;  the  mo 
cha  ftone. 

d.  Semi-tranfparent,  with  red  dots ;  Gemma  dlvi 
Stepham.     When  the  points  are  very  minute,  fo 
as  to  give   the    ftone  a  red  appearance,  it  is 
by  fome  called  Sartlea. 

e.  Semi  tranfparent,  with  clouds  of  an  orange  co 
lour. 

f.  Deep  red  or  violet,  and  femi-tranfparent. 

f.  Of  many  colours,  or  variegated. 
.  Black. 
IX.  Common  Flint ;  Pyromachus. 

This  in  reality,  is  of  the  fame  fubftance  as  the  agate  ; 
but  as  the  colours  are  not  fo  ftriking  or  agreeable, 
it  is  commonly  confidered  as  a  different  fub- 
ibince. 

a.  Blackifh  grey,  from  the  province  of  Skone. 
/'.  Yellow  femi-traufparent,  from  France. 

f.  Whitifti  grey. 

iL  Yellowiih  brown. 


*  On  the  fide  of  a  hill  near  the  church  of  Rothea 
in  Moray,  is  a  quantity  of  fine  agate  of  elegant  red  and 
white  colours.  It  is  very  hard,  heavy,  of  a  fmooth 
uniform  texture,  and  of  a  considerable  brightnefs  ;  in 
which  the  red  are  remarkably  clear,  and  finely  mixed 
and  ihaded  through  the  ftone.  Mr  Willamsfays  that 
this  is  the  largeft  and  moil  beautiful  agate  rock  he 
ever  favv  ;  and  fo  fine  and  hard  us  to  be  capable  of  the. 
bigheft  luftre  in  polifliing. 

When 


C   91    3 

When  the  flints  are  fmiall,  they  are  in  Eng 
land  called /<?££/>.!•;  and  the  Swedilh  failors,  who 
take  them  as  ballaft,  call  \\izmjingel. 
X.  Chert ;  Petrofikx,  Lapis  Corneus.     The  bornjlein  of 

the  Germans. 

This  is  of  a  coarfer  texture  than   the  preceding, 

and  alfo  lefs  hard,  "which  makes  it  confequently 

not  fo  capable  of  a  polifh.     It  is  femi-tranfparent 

•  at  the  edges,  or  when  it  is  broke  into  very  thin 

pieces. 

a.  Chert  of   a  flefh  colour,    from  Carl-Scakt,  at 
the  filver-mine  of  Salberg,  in  the    province  of 
Weftmanland. 

b.  Whitilh  yellow,  from  Salberg. 

c.  White,  from  Kriftierfberg,  at  Nya  Kopparberget 
in  Weftmanland. 

d.  Greeniih,    from  Preftguvfm,    at    Hellefors    in 
Weftmanland. 

Chert  runs  in  veins  through  rocks,  from  whence 
its  name  is  derived.  Its  fpecific  gravity  is  from 
2590  to  2700;  In  the  fire,  it  whitens  and  de 
crepitates  like  filex,  but  is  generally  fo  fufible  as 
to  melt  per  fe.  It  is  not  totally  dillblved  in  the 
dry  way  by  the  mineral  alkali ;  but  borax  and 
microcofmic  fait  difiblve  it  without  effervefcence, 
Its  appearance  is  duller  and  lefs  tranfparent  than 
common  flint.  The  reddifti  Petro-filex  ufed  in 
the  Count  de  Lauragar's  procelain  manufacture, 
and  called  there  felt  fpat.  contained  72  per  cent. 
of  filex,  22  of  argill,  and  6  of  calcareous  earth. 

There  are  not  yet  any  certain  characters  known 
by  which  the  cherts  and  jafpers  may  be  di- 
ftinguifhed  from  each  other:  by  light,  how 
ever,  they  can  eafily  be  clifcerned,  viz.  the  for 
mer  (the  cherts)  appearing  tranfparent,  and  of 
a  fine  fparkling  texture,  on  being  broken ; 
whereas  the  jafper  is  grained,  dull,  and  opaque, 
liaving  the  appearance  of  a  dry  clay;  The  cheit 

is 


C    92    1 

is  alfo  found  forming  larger  or  fmaller  veins,  or 
in  nodules  like  kernels  in  the  rocks  ;  whereas  the 
jafper,  on  the  contrary,  fometimes  conftitutes  the 
chief  fubftance  of  the  higheft  and  moft  extend 
ed  chain  of  mountains.  The  chert  is  likewife 
found  plentifully  in  the  neighbourhood  of  fcaly 
limeftone,  as  flints  in  the  ftrata  of  chalk.  What 
connection  there  may  be  between  thefe  bodies, 
perhaps  time  will  difcover. 

But  flints  and  agates  being  generally  found  in 
loofe  and  fmgle  irregular  nodules,  and  hardly  in 
rocks,  as  the  chert,  it  is  a  circumftance  very  in- 
fufficient  to  eftablifh  a  difference  between  them ; 
for  there  is  the  agate-ftone,  near  Conftantinople, 
running  vein-like  acrofs  the  rock  with  its  coun 
try  of  the  fame  hardnefs,  and  as  fine  and  tranf- 
parent  as  thofe  other  agates  which  are  found  in 
round  nodules  at  Deux-ponts.  We  muft,  there 
fore,  content  ourfelves  with  this  remark  con 
cerning  flints,  viz.  That  they  feem  to  be  the 
only  kind  of  ftone  hitherto  known,  of  which  a  very 
large  quantity  has  been  formed  in  the  ihape  of 
loofe  or  feparate  nodules,  each  furrounded  with 
its  proper  cruft  ;  and  that  the  matter  which  con 
ftitutes  this  cruft  has  been  feparated  from  the 
reft  of  the  fubftance,  in  like  manner  as  fandiver 
or  glafs-gall  feparates  from,  and  fwims  upon, 
glafs,  during  its  vitrification ;  though  fometimes 
the  formation  of  this  cruft  may  be  prevented  by 
the  too  fudden  hardening  of  the  matter  itfelf. 

Other  fpecies  of  ftones,  which  are  found  in  loofe 
pieces  or  nodules,  except  ores  and  fome  forts 
of  ftalactites,  fhow  evidently  by  their  cracks, 
angles,  and  irregular  figures,  that  they  have  been 
torn  from  rocks,  rolled  about,  and  rubbed  againft 
one  another  in  torrents,  or  by  fome  other  violent 
motions  of  water. 

That 


[    93     ] 

That  flints  had  originally  been  in  a  foft  Hate, 
M.  Cronftedt  obferves,  is  eafy  to  be  feen  in  the 
.Egyptian  pebbles,  which  have  impreffions  of 
fmall  ftones,  fand,  and  fometimes,  perhaps,  grafs  ; 
which,  however,  have  not  had  any  ingrefs  into 
the  very  flint,  but  feem  only  to  have  forced  the 
above  agate  gall  or  cruft  out  of  the  way. 

$4-     VJafpers 

JASPER,  jafpis,  (the  diafpro  of  the  Italians),  is  a 
name  given  to  all  the  opaque  flints  whole  texture  re- 
fembles  dry  clay  and  which  have  no  other  known  qua 
lity  whereby  they  may  be  dirlinguifhed  from  other 
flints,  except  that  they  may  be  more  eafily  melted  in 
the  fire  ;  and  this  quality  perhaps  may  proceed  from 
the  heterogeneous  mixture,  probably  of  iron. 

I.  Pure  jafper  ;  which  by  no  means  yet  known  can 
be  decompounded. 

a.  Green  with  red  fpecks  or  dots :  the  helio 
trope,  or  blood-ftone.  1.  Green :  £.  Reu* 
d.  Yellow,  e.  Red  with  yellow  fpots  and 
veins,  f  Black. 

II.  Jafper  containing  iron  :  Jafpis  martiales  S'mople. 
A  coarfe -grained. 

a.   Red  and  reddifh  brown  ;  finople. 
B.  Steel-grained,  or  fine-grained. 

a.  Reddifh  brown  ;  looks  like  the  red  ochre  or 
chalk  ufed  for  drawing ;  and  has  partition 
veins,  which  are  unctuous  to  the  touch,  like 
a  fine  clay,  and  other  like  kinds. 

C.  Of  a  folid  and  Ihining  texture,  like  a  flag. 

a.  Liver-coloured  ;  and,  b,  Deep  red.  c.  Yel 
low.  This  laft  mentioned,  when  calcined'*,  is 


*  Near  Portfoy  in  BaniF-ftiire  is  an  extenfive  rock 
of  jafper  ;  fome  parts  of  which  contain  a  beautiful 
mixture  of  green  and  red,  which  appear  finely  fhaded 

and 


E    94    3 

attracted  by  the  loadftone :  and  being  affayed, 
yields  from  12  "to  15  percent,  of  iron. 

§  5.     Felt-fpars. 

I.  Rhombic  quartz;  Spatum  fcintiflatu. 

This  has  its  name  from  its  figure,  but  feems  to  be 
of  the  fame  fubftance  as  the  jafper.  We  have  not, 
however,  ranked  them  together,  for  want  of  trne 
marks  to  diftinguifh  the  different  forts  of  the  flin 
ty  tribe  from  one  another. 
This  kind  is  found, 

1.  Sparry. 

a.  White.     £.  Reddifti  brown,     c.  Pale  yellow. 
d.  Greenifh. 

2.  Cryftallized. 

a.  In  feparate  or  diftincT:  rhomboidal  cryftals. 

II.  Labradore  ftone  ;  Spatum  rutilum  ver/ico'or. 

Its  colour  is  commonly  of  a  light  or  of  a  deep 
grey,  and  moftly  of  a  blackifh  grey  :  but  when 
held  in  certain  pofitions  to  the  light,  difco- 
vers  different  varieties  of  beautiful  fhining  co 
lours,  as  lazuly-blue,  grafs-green,  apple-green, 
pea-green ;  and  feldom  a  citron-yellow ;  fome 
have  an  intermediate  colour  betwixt  red-copper 
and  tombac-grey ;  befides  other  colours  between 
grey  and  violet.  Thefe  colours  are  feen  for  moft 
part  in  fpots ;  but  fometimes  in  ftripes,  on  the 
ifame  piece. 

III.  White  feltlpar  ;  Terra  Silicea  Magnefia  &  fcrro  m- 
timk  mixfa. 

This  ftone  has  been  defcribed  by  Mr  Bayen  :  and  is 
found  at  St  Marie  aux  mines  in  Lorrain, — It  is 


and  clouded  through  the  body  of  the  ftone  when  po- 
lifhed.  Mr  Williams  is  of  opinion  that  it  would  be  a 
very  valuable  quarry  if  worked. 

of 


[    95     ] 

of  a -white  opaque  colow,  ipotted  witli  ochre  on 
the  outfide. 


§  6.     Of  the  Garnet  Kinds. 

THE  fubftances  of  this  ge*w  (which  is  confidered  by 
Cronftedt  as  an  order)  are  analogous  to  gems ;  fmce 
all  thefe  are  compofed  of  the  filiceous,  calcareous,  and 
argillaceous  earths,  with  a  greater  or  lefs  proportion 
of  iron.  The  opaque  and  black  garnets  contain  about 
20  hundredths  of  iron :  but  the  diaphanous  ones  only 
two  hundredths  of  their  weight,  according  to  Berg 
man.  The  garnets,  properly  fo  called,  contain  a  great 
er  quantity  of  filiceous  earth  than  the  fhirls,  and  both 
are  now  juftly  ranked  with  the  filiceous  earths. 

The  fpecies  are, 
I.  Garnet;  Granattis. 

This  is  a  heavy  and  hard  kind  of  (lone,  cryftallizing 
in  form  of  polygonal  balls,  and  moftly  of  a  red,  or 
reddifh  brown  colour. 

A.  Garnet  mixed  with  iron  ;  Granatus  martialis. 

1.  Coarfe -grained  garnet-ftones,  without  any  par 
ticular  figure;  in  Swedifli  called  Granatberg  ; 
in  German,  Granatjlsm. 

a.  Reddifh-brown  garnet,  b.  Whitifii  yellow. 
c.  Pale  yellow. 

2.  Cryftallized  garnet. 

a.  Black,  b.  Red :  femi-tranfparent,  and  crack 
ed;  tranfparent.  c.  Reddifli-yellow ;  tranf- 
parent ;  the  jacinth,  or  hyacinth,  d.  Red 
difh  brown,  e.  Green,  f.  Yellowifh-green* 
g.  Black. 

B.  Garnet  mixed  with  iron  and  tin. 

1.  Coarfe-grained,    without    any  particular    fi 
gure. 

a.  Blackifh-browsn. 

2.  Cryftallized.          , 
a.  Blackiih-brown. 

I.  Light 


C    96    ] 

I.  Light-green  or  white. 
C.  Garnet  mixed  with  iron  and  lead. 
i.  Cryftallized. 

a.   Reddifh-brown. 
II.  Cockle,  or  fhirl.       Corneus  eryflalllzatus   Wallerii ; 

Stannum  cryjlallis  columnaribus  n'tgris  Linnai. 
This  is  a  heavy  and  hard  kind  of  (tone  which  fhoots 
into  cryftals  of  a  prifmatical  figure,  and  whofe 
chief   colours  are  black  or  green.      Its  fpecific 
gravity  is  the  fame  as  the  garnets,  viz.  between 
3000  and  3400,  though  always  proportionable 
to  their  different  folidity. 
A.  Cockle,  or  fhirl,  mixed  with  iron. 

1.  Coarfe,  without  any  determined  figure. 
a.  Green. 

2.  Sparry. 

a.  Deep  green,  (the  mother  of  the  emeralds)., 

from  Egypt. 
I.  Pale  green. 
c.  White.     This  occurs  very  frequently  in  the 

fcaly  limeftones ;    and    its    colour  changes 

from  deep  green  to  white,  in  proportion  as  it 

contains  more  or  lefs  of  iron. 

3.  Fibrous,  ftriated  cockle,  or  fhirl :  it  looks  like 
fibres  or  threads  made  of  glafs. 

A.  Of  parallel    fibres,     a.   Black.     I.  Green 
c.  White. 

B.  Of  concentrated  fibres  :  The  ftarred  cockle 
or  fhirl,  from  its  fibres  being  laid  ftellarwife 

a.  Blackifh  green.    />.  Light  green,     c.  White 

4.  Cryftalli/ed  cockle,  or  fhirl. 

a.  Black.  To  this  variety  belong  moft  of  thofi 
fubftances  called  imperfia  a/befit  ;  and  as  th< 
cockle  perfectly  refembles  a  flag  from  at 
iron  furnace,  both  in  regard  to  its  metallic 
contents  and  its  glaiTy  texture,  it  is  no  won 
der  that  it  is  not  foft  enough  to  be  takei 
for  an  a&eftus.  It  has,  however,  only  fo: 

2  til. 


E    97     ] 

the  fake  of  its  ftru<5hire,  been  ranked  among 
the  afbefti.  The  ftriated  cockle,  cr  fliirl, 
compared  to  the  aibefti,  is  of  a  fhining  and 
angular  furface  (though  this  fometimes  re 
quires  the  aid  of  the  magnifying-glafs  to 
be  difcovered)  always  fomewhat  tranfpa- 
rent,  and  is  pretty  eaiily  brought  to  a  glaf? 
with  the  blow-pipe,  without  being  confum- 
ed  as  the  pure  afbefti  feem  to  be. 

b.  Deep  green. 

c.  Light  green. 

d.  Reddilh    brown.      The  tanffsteln  is  of  this 
colour,  and  confifls  of  two  hexagonal  cry- 
ftals  of  cockle  grown  together  in  form  of  a 
crofs  ;  this  the  Roman  Catholics  wear  as  an 
amulet,  and  is  called  in  Latin  lapis  crucifer, 
or  the  crofs  (lone. 

The  figure  of  the  cockle  cryftals  is  uncertain, 
but  always  prifmatical :  the  cockle  from  Yxfio, 
at  Nya  Kopparberg,  is  quadrangular  :  the  French 
kind  has  nine  fides  or  planes;  and  the  tauffsteia 
is  hexagonal. 

The  naine  cockle  for  thefe  fubflances  is  an  old 
Cornifh  mineral  name  ;  but  is  alfo  given  fometimes 
to  other  very  different  matters. 

There  is  not  in  England  any  great  quantity  of 
fpecies  of  cockles  ;  the  chief  are  found  in  the  tin 
mines  of  Cornwall,  and  fome  fine  cryftallizecl 
kinds  have  been  brought  from  Scotland. 

The  Englifli  mineral  name  of  call,  has  been  ufed 
by  fome  authors  as  fynonymous  with  cockles,  and 
they  are  confounded  together  at  the  mines ;  but 
the  call,  definitely  fpeaking,  is  the  fubftance  call 
ed  wolfram  by  the  Germans,  &c. 

Garnets,  though  fmall,  are  often  found  in  mica 
ceous  (tones  in  England  j  but  extreme  good  gar 
nets  are  found  in  great  plenty  alfo  in  like  ftones 
in  Scotland. 

K  III. 


gil,  ar 
IV.  Silic 


III.  Rowley  rag,  (Kirivan).  This  flone  is  of  a 
dufky  or  dark  grey  colour,  with  numerous  minute 
iliining  cryftals.  Its  texture  is  granular  :  by  ex- 
pofure  to  the  air  it  acquires  an  cchry  cruft.  Its 
fpecilic  gravity  is  2748.  Heated  in  an  open  fire 
it  becomes  magnetic.  In  ftrong  heat  it  melts 
fer  fe,  but  with  more  difficulty  than  bafaltes. 
According  to  Dr  Withering's  analyfis,  100  parts 
of  it  contain  47,5  of  filiceous  earth,  32,5  of  ar- 
;il,  and  20  of  iron. 

Siliceous  muriatic  fpar,  (Id)  This  done  is  of 
a  hard,  folid,  and  fparry  texture ;  of  a  grey, 
cchry,  dull  colour,  but  internally  bright.  It  gives 
fire  with  fteel :  yet  it  eifervefces  with  acids.  In 
a  ftrong  heat  it  grows  brown  ;  but  at  la  ft  it  melts 
per  fe.  One  hundred  parts  of  this  ftone  contain 
fifty  parts  of  lilex  :  the  remainder  is  mild  mag- 
reiia  and  iron ;  but  in  what  proportion  is  not 
mentioned  ( See  Journal  de  PJmfijyuet  Supplement, 
vol.  xiii.  p.  216. 

V.  Turky  ftone  ;  cos  Tunica.  (LI.)     This  ftone  is 
cf  a  dull  white  co^ur,  and  often  of  an  uneven 
colour,  feme  pans  appearing  more  compadt  than 
others,  fo  that  it  is  in  ibme  meafure  ihattery.     It 
is  ufed  as  a  whetilone  :  and  thofe  of  the  fir.eft  grain 
are  the  heft  hones  for  the  rnoft  delicate  cutting 
tools,  and  even  for  razors,  lancets,  &c.      Its  fpe- 
ciftc  gravity  is  2598.      It   gives   fire  with  fteel ; 
yet  efFervefces  with  acids.      Mr    Kirwan  found 
that  ico  parts  of  it  contains  25  of  mild  calcareous 
earth,  and  no  iron.     There  probably  are  two  forts 
cf  ftones  known  by  this  name,  as  Mr  Wallerius 
affirms,  that  which   he  clefcribes  neither  to  give 
fire  with  fteel  nor  efFervefce  with  acids. 

VI.  Ragg  ftor.e.     The  colour  of  this  ftone  is  grey. 
Its  texture  is  obfcurely  laminar,  or  rather  fibrous, 
but  the  lamince  or  fibres  confift  of  a  congeries  of 
trains  of  a  quartzy  appearance,  coarfe  and  rough. 

Its 


[    99     3 


Its  Specific  gravity  is  2729.  It  efFervcfces  with 
acids  ;  and  gives  fire  with  fteel.  Mr  Kirwaa 
found  it  to  contain  a  portion  of  mild,  calcareous 
earth,  and  a  fmall  proportion  of  iron.  It  is  ufcd 
as  a  whet-ftone  for  coarfe  cutting  tools. 

[The  filiceous  grit,  cos  arenariusy  and  other 
compounds  of  the  filiceous  earth,  £c.  will  be 
found  in  a  fubfequent  divifion  of  this  article.] 

Oyervations  on  the  economical  Ufes  of  the  Siliceous  Order* 

THE  Europeans  have  no  farther  trouble  with  th'j 
precious  ftones  than  either  to  cat  them  from  their  na 
tural  or  rough  figure,  or  to  alter  them  when  they  have 
been  badly  cut  in  the  Eall  Indies j  in  which  latter  cir- 
cumftances  they  are  called  labora  :  and  it  may  be  oh- 
fervcd,  that  for  cutting  the  ruby,  fpinell,  balks,  and 
chryfolite,  the  oil  of  olive  is  required,  infte.id  or  any 
other  liquid,  to  be  mixed  with  the  diamond  powder, 
in  the  fame  manner  as  for  cutting  the  diamond  it- 
ftlf. 

If  the  petty  princes  in  thofe  parts  of  the  Indies, 
where  precious  ftones  are  found,  have  no  other  power 
nor  riches  proportionable  to  the  value  of  theie  gems, 
the  reafon  of  it  is  as  obvious  as  of  the  general  weak- 
nefs  of  thofe  countries  where  gold  and  filver  abound, 
•viz.  becaufe  the  inhabitants,  placing  a  falfe  confidence 
in  the  high  value  of  their  poffeffions,  neglect  ufeful 
manufactures  and  trade,  which  by  degrees  produces  a 
general  idlenefs  and  ignorance  through  the  whole 
country. 

On  the  other  hand,  perhaps,  fome  countries  might 
fafely  improve  their  revenues  by  fuch  traffic.  In 
Saxony,  for  example,  there  might  probably  be  other 
gems  found  befides  aqua  marines  and  topazes  ;  or 
even  a  greater  trade  carried  on  with  thefe  than  at  pre- 
fent,  without  danger  of  bad  confequences,  efpecially 
under  the  direction  of  a  careful  and  prudent  govern 
ment. 

K  2  The 


C       IGO       ] 

The  half-precktu  ftones,  fo  called,  or  gems  of  lefs 
value,  as  the  common  opal,  the  onyx,  the  chalcedony, 
the  cornelian,  and  the  coloured  and  colourlefs  rock 
cryftals,  have  been  employed  for  ornaments  and  econo 
mical  utenfils,  in  which  the  price  cf  the  workmanfhip 
greatly  exceeds  the  intrinfic  value  cf  the  (tones.  The 
ancients  ufed  to  engrave  concave  and  convex  figures 
on  them,  which  now  a-days  are  very  highly  valued,  but 
often  with  lefs  reafon  than  modem  performances  cf 
the  fame  kind.  Thefe  ftones  are  worked  by  means  of 
emery  on  plates  and  tools  cf  lead,  copper,  and  tin,  or 
with  other  ind  ruments :  but  the  common  work  on 
agates  is  performed  at  Oberftein  with  grind-Mones  at 
a  very  cheap  rate.  When  once  fuch  a  manufactory  is 
eftabliihed  in  a  country,  it  is  neceffary  to  keep  it  up 
with  much  induftry  and  prudence,  if  we  would  wifh  it 
to  iiii-mount  the  caprice  of  fafhions  ;  fmce,  how  much- 
icev.cr  the  natural  beauties  of  thcfe  itonek  feem  to 
plead  l\r  tk;,:v  pre-eminence,  they  will  at  feme  periods 
unavoidably  fink  in  the  eikem  cf  mankind  j  but  they 
will  likewiie  often  recover,  and  be  reilored  to  their 
former  value. 

The  grindflones  at  Oberfiein  are  cf  a  red  cclcur, 
and  of  itich  particular  texture,  that  they  neither  be 
come  fmooth,  nor  are  they  of  too  loofe  a  ccmpofitior. 

Moft  part  cf  the  flinty  tribe  is  employed  for  ma- 
Jang  glafs,  as  the  quartz,  the  flints,  the  pebble?,  and 
the  quartzofe  fands.  The  quartz,  however,  is  the 
bell ;  and  if  ufed  in  due  proportion  with  refpect  to  the 
alkali,  there  is  no  danger  of  the  glafs  being  eafily  at 
tacked  by  the  acids,  as  has  fometimes  happened  with 
glafs  made  of  other  fubitances,  of  whicli  we  had  an 
inftance  cf  bottlts  filled  with  Khenifh  and  Mofelle 
wines  during  the  time  cf  a  voyage  to  China. 

In  the  fmelting  of  copper  ores,  quartz  is  ufed,  to 
render-  the  flag  glaify,  or  to  vitrify  the  iron  ;  quartz 
being  more  ufeful  than  any  other  ftor.e  to  prevent  the 
calcination  of  the  rcetah 

The 


I     1 01     ] 

The  quartzofe  fand  which  conftitutes  part  of  many 
ftones,  and  is  alfo  ufed  in  making  crucibles  and  fuch 
veifels  contributes  mod  of  all  to  their  power  of  refill 
ing  fire. 

It  appears  likewife  probable  that  the  quartzofe: 
matter  makes  the  grind  and  whetftone  fit  for  their  in 
tended  purpofes.  (Magellan.} 

Order  V.     The  ARGILLACEOUS  EARTHS. 

THE  principal  character  whereby  thofe  may  be  di- 
ftinguifhed  from  other  earths  is,  that  they  harden  in 
the  fire,  and  are  compounded  of  very  minute  particles, 
by  which  they  acquire  a,  dead  or  dull  appearance  when, 
broken. 

I.  Argilla  aerala  ;  lac  luna*. 

This  fancimi  name  was  heretofore  thought  to  de 
note  a  very  fine  fpecies  of  calcareous  earth  ;  but 
Mr  Screber  has  lately  ftiown,  that  the  earth  to 
which  this  name  is  given,  is  a  very  uncommon 
fpecies  of  argill.  It  is  generally  found  in  fmall 
cakes  of  the  hardnefs  of  chalk  j  and  like  that,  if 
marks  white.  Its  hardnefs  is  nearly  as  that  to 
fteatites,  and  it  does  not  feel  fo  fat  as  common 
clay  does.  Its-  fpecific  gravity  is  1669  ;  its  co 
lour  fnow  white.  When  examined  with  a  micro- 
fcope,  it  is  found  to  conlifl  of  fmall  tranfpa- 
rent  cryftals;  and  by  his  experiments  it  appears 
plainly  to  be  an  argill  faturated  with  fixed  air. 
It  effervefces  with  acids,  and  contains  a  very  fmall 
proportion  of  calcareous  earth  and  fome times  of 
gy.pium,,  befides  fonie  feeble  traces  of  iron.  It 
is  found  near  Halles. 

II.  Porcelain  clay  ;    Terra   porcellanea,  vulgo  Argylla 

apyray  very  refractory  ;  the  kaolin  of  the  Chinefe», 
CL)   Pure. 

A.  Diffufible  in  water. 
i.  Coherent  and  dry. 
A.  White. 

K  3.  2..  Friable" 


[       102      ] 

2.  Friable  and  lean. 

a.  White. 

(2.)  Mixed  with  phlogifton. 
A.  DifFufible  in  water. 

a.  White  and  fat  pipe  clay.  I.  Of  a  pearl  colour. 
r .  Bluifti  grey.  cL  Grey.  e.  Black.  /.  Violet. 
Thefe  contain  a  phlogifton,  which  is  difcovered 
by  expofmg  them  to  quick  and  ftrong  fire,  in 
which  they  become  quite  black  interiorly,  afTuming 
the  appearance  of  the  common  flints,  not  only  in 
regard  to  colour,  but  alfo  in  regard  to  bardnefV: 
but  if  heated  by  degrees,  they  are  flrft  white,  and 
afterwards  of  a  pearl  colour.  The  fatter  they  feem 
to  be,  which  may  be  judged  both  by  their  feeling 
Tmooth  and  unctuous,  and  by  their  flnning  when 
fcraped  with  the  nail,  they  contain  a  larger  quanti 
ty  of  the  inflammable  principle.  It  is  difficult  to 
determine,  whether  this  ftrongly  inherent  phlogifton 
be  the  caufe  of  the  abovementioned  pearl-colour, 
or  prevents  them  from  being  burnt  white  in  a  ftrong 
fire  ;  yet  no  heterogeneous  fubftance  can  be  extracl- 
cd  from  them,  except  fand,  which  may  be  feparated 
from  fome  by  means  of  water  ;  but  which  fand  does 
not  form  any  of  the  condiment  parts  of  the  clays. 
If  they  be  boiled  in  aqua  regis  in  order  to  extract 
any  iron,  they  are  found  to  lofe  their  vifcofity. 
Ill,  Stone-marrow;  Lithomarga  Kiffikil  of  the  Tar 
tars. 

1.  When  dry,  it  is  as  fat  and  ilippery  as~  foap ; 
but, 

2.  Is  not  wholly  diffufible  in  water,  in  which  it 
only  falls  to  pieces,  either  in  large  bits,  or  re- 
femhles  a;  curd-like  mafs. 

3.  In  the  fire  it  eafily  melts  to  a  white  or  reddiih 
frothy  flag,,  confequently  is  of  a  larger  volume 
than  the  clay  was  before  being  fuied. 

4.  It  breaks  into  irregular  fcaly  pieces. 

A,  Of  coarfe  particles  :.Coarfe  ftone -marrow. 

t:.  Ore}; 


a.  Grey, 

B.  Whitifh   yellow,   from  the  Ciim  Tartary, 
where  it  is  called  keffekil,  and  is  faid  to-  be 
ufed  for  wafhing  inftead  of  foap. 
£.  Of  very  fine  particles ;  fine  ftone-marrow. 

a.  Yellowifh  brown ;  Terra  Lemma. — Is  of  a 
fhining  texture,  falls  to  pieces  in  the  water 
with  a  crackling  noife  ;  it  is  more  indura 
ted  than  the  preceding,  but  has  otherwife  the 
fame  qualities. 
IV.  Bole,  (iron  clay.) 

This  is  a  fine  and  denfe  clay  of  various  colours, 
containing  a  great  quantity  of  iron,  which  makes 
it  impoflible  to  know  the  natural  and  fpecifical 
qualities  of  the  bone  itfelf,  by  any  eafy  method 
hitherto  in  ufe.  It  is  not  eafily  foftened  in  wa 
ter,  contrary  to  what  the  porcelain  and  the  com 
mon  clays  are,  ( I.  and  VI. )  ;  but  either  falls  to 
pieces  in  form  of  fmall  grains,  or  repels  the  wa 
ter,  and  cannot  be  made  ductile.  In  the  fire  it 
grows  black,  and  is  then  attracted  by  the  loadftone. 
A.  Loofe  and  friable  boles,  or  thofe  which  fall  to  a> 
powder  in  water. 

a.  Flefh-coloured  bole. 

b.  Red. 

1.  Fine  ;  Bolus  Ar menus, 

2.  Coarfe  ;  JBolus  communis  officinalis. 

3.  Hard  ;   Terra  rulrica. 
c*  Green  ;  Terre  verte. 

1.  Fine. 

2.  Coarfe. 

d.  Bluiih  grey,  is  ductile  as  long  as  it  is  in  the 
rock,  but  even  then  repels  the  water  ;  it  con 
tains  40  per  cent,  of  iron ;  which  metal  be 
ing  melted  out  of  it  in  a  clofe  veflel,  the  iron 
cryftallizes  on  its  lurface. 

t.  Grey. 

i.  Chryftal- 


C    104    ] 

.      I.  Cryftallized  in  a  fpherical  polygonal  fi 
gure. 

2.  Of  an  unde terminate  figure. 
JB.  Indurated  bole. 

A.  Of  no  vifible  particles. 

This  occurs  very  often  in  form  of  flate,  or 
layers,  in  the  earfh  ;  and  then  is  made  ufe  of  as 
an  iron  ore.  However,  it  has  ufually  been 
corifidered  more  in  regard  to  its  texture  than 
to  its  conftituent  parts ;  and  has  been  called 
jlats,  in  common  with  feveral  other  earths 
which  are  found  to  have  the  fame  texture. 
a.  Reddifh-brown  ;  in  moft  collieries,  betweea 

the  feams  of  coal. 
'   b.  Grey. 

B.  Of  fcaly    particles. — The    hornblende   of   the 
Swedes. 

It  is  diflinguifhed  from  the  martial  glimmer, 
or  mica,  by  the  fcales  being  lefs  ihining,  thicker,- 
and  rectangular. 
a.  Black. — This,   when    rubbed  fine  gives  a 

green  powder. 
b-  Greenifh.. 
V.  Zeolyte. 

This  is  defcribed  in  its  indurated  data  in  the 
Tranfactions  of  the  academy  of  fciences  at  Stock 
holm  for  the  year  1756,  and  there  arranged  as 
a  Rone  fut  generis  in  regard  to  the  following  qua 
lities. 

1.  It  is  a  little  harder  than  the  fluors  and  the* 
other  calcareous  fpars ;  it  receives,  however, 
fcratches  from  the  fteel,  but  does  not  itrike 
fire  with  it. 

2.  It  melts  eafily  by  itfeif  in  the  fire,  with  a, 
like  ebullition  as  borax  does,  into  a  white 
frothy  flag,  wbich  cannot  without  great  dif 
ficulty  be  brought  to  a  iblidity  and  tranfpa- 


C     '05     ] 

3.  It  is  more  eafily  ditfblved  in  the  fire  by  the 
mineral  alkali  (fai  fod*),  than  by  borax  or 
the  microcofmic  fait. 

4.  It  does  not  ferment  with  this  lad  fait,  as  lime 
does ;  nor  with  the  borax,  as  thofe  of  the 
gypfeous  kind, 

5.  It  diflblves  very  flowly,  and  without  any 
effervefcence,  in   acids,  as   in  oil  of  vitriol 
and  fpirit  of  nitre.     If  concentrated  oil  of 
vitriol  be  poured  on  pounded  zeolites,  a  heat 
arifes,  and  the  powder  unites  into  a  mnis. 

6.  In  the  very  moment  of  fufion  it  gives  a 
phofphoric  light. 

There  have  lately  been  difcovered  fome  of 
the  zeolites,  particularly  at  Adelfors's  gold 
mines    in  SmolanJ,    in  Sweden ;  of  which 
fome  forts  do  not  melt  by  themfelves  in  the 
lire,  bat  diilblve  readily  in  the  acid  of  nitre, 
and  are  turned  by  it  into  a  firm  jelly. 
The  zeoiyte  is  found  hi  an  indurated  ftate : 

(i.)  Solid,  or  cfnovifible  particles. 

A.  Pure. 

a.  White. 

B,  Mixed  with  filver  and  iron. 

a.  Blue,  Lapis  laxuli. 

(2.)  Sparry  zeolite.  Th:s  refembles  a  calcareousfpar, 
though  it  is  of  a  more  irregular  figure,  and  is  more 
brittle. 

a.  Light  red,  or  orange-coloured. 
(3.)  Cryftalliled  zeolite.      This  is  more  common 
than  the  two  preceding  kinds;  and  is  found, 

A.  In  groupes  of  cryftals,  in  form  of  balls,  and 
with  concentrical  points. 

a.  Yellow, 

b.  White. 

B.  Prifmatical  and  truncated  cryftal?* 

a.     White. 

C.  Capillary 


[     io6     ] 

C.  Capillary  cryftals,  which  are  partly  united  in 
groupes,  and  partly  feparate.  In  this  latter 
accretion  they  refemble  the  capillary  or  fea 
thery  filver  ere:  and  are  perhaps  iometimes  call* 
z&fbs  ftrri,  at  places  where  the  nature  of  that 
kind  of  ftone  is  not  yet  fully  known, 

a.  White. 
VI.  Tripoli. 

This  is  known  by  its  quality  of  rubbing  or  wear* 
ing  hard  bodies,  and  making  their  iuriaces  to 
ihine  ;  the  particles  of  the  tripoli  being  fo  line 
us  to  leave  even  no  (cratches  on  the  furface.  This 
effect,  which  is  called  poltjkirtgt  may  likewife  be 
cffecled  by  other  fine  clays  wjien  they  have  been 
burnt  a  little.  The  tripoli  grows  fbxnewhat 
harder  in  the  fire,  and  is  very  refractory  :  it  is 
with  difficulty  diflblved  by  borax,  and  ftill  with 
greater  difficulty  by  the  microcofrnic  fait.  It 
becomes  white  when  it  is  heated :  when  crude, 
it  imbibes  water,  but  is  not  difiuflble  in  it :  it 
lafteslike  common  chalk,  and  is  rough  and  fandy 
between  the  teeth,  although  no  fund  can  by  any 
means  be  feparated  from  it.  It  has  no  quality 
common  with  any  other  kind  of  earth,  by  which 
it  might  be  ccnfidered  as  a  variety  of  any  other. 
That  which  is  here  deicribed  is  of  a  yellow  co 
lour,  and  is  fold  by  druggtfts.  This  kind  of 
tripoli  has  been  lately  discovered  in  Scotland. 
But  the  rotten- fione,  fo  called,  is  another  fort 
found  in  England,  viz.  in  Derbyfhire,  It  is 
in  common  tife  in  England  among  workmen  for 
all  forts  of  finer  grinding  and  polifhing,  and  is 
alfo  fometimes  ufed  by  lapidaries  for  cutting  of 
ftones,  &c. 
The  tripoli  is  found, 

i.  Solid :  of  a  rough  texture. 

a.  Brpwn. 

b.  Yeilowifk 

c.  Spotted 


[     107     1 

e.  Spotted  like  marble. 
2.  Friable  and  compact. 

a.  Granulated. 

b.  Brown. 

c.  Yellowifli. 

VII.  Common  clay,  or  brick  clay. 

This  kind  may  be  diilinguifhed  from  the  other  clays 
by  the  following  qualities  : 

1.  In  the  fire  it  acquires  a  red  colour,  more  or 
lefs  deep. 

2.  It  melts  pretty  eafily  into  a  greenifli  glafs. 

3.  It  contains  a  fmalt  quantity  of  iron  and  of  the 
vitriolic  acid,  by  which  the  preceding  effects  are 
produced. 

It  is  found, 

A,  Diffufible  in  water. 
i.  Pure. 

a.   Red  clay. 

/;.  Fleih-coloured,  or  pale-red. 
c.    Grey. 
</.  Blue. 
f.  White. 

f.  Fermenting  clay. 

2  Mixed  with  lime.     See  MARLE,  above, 
£.  Indurated. 

1.  Pure. 

a.  Grey  flate. 

b.  Redflaty. 

2.  Mixed  with  phlogifton,  and  a  great  deal  of 
the  vitriolic  acid.      See  ALUM  Ores,  above. 

3.  Mixed  with  lime.   Sec  LIME,  above. 

VIII.  Argillaceous  fiflile  (tones. 

Thefe  and  many  other  different  kinds  cf  earth 
have  been  comprehended  under  the  denomination 
Qfjchiftt}  but  to  avoid  ambiguity  we  will  confine 
this  name  to  ftones  of  the  argillaceous  kind. 
i.  The  bluifli  purple  fchiilus,  or  common  roof 

(late ;  fchiflus  tegit/aris. 

Its 


[     io8     ] 

Its  colour  varies  to  the  pale,  to  the  {lightly 

purple,  and  to  the  bluifh. 

a.  The  dark-blue  £zte,f<:hi/liis  fcriptorius. 

2.  The  pyritaceous  fchiftus. 

This  is    of  a    grey  colour,  brown,    blue,  or 
; '  black. 

3.  The  bituminous  fchiftus. 

This  is  generally  black,  of  a  lamellar  tex 
ture,  and  of  different  degrees  of  hardnefs. 

4.  Flag  ftone. 

This  is  of  a  grey,  yellowifh,  or  reddifh  white 
colour. 

5.  The  argillaceous  grit. 

This  is  called  alio  fandjlone  and  free  Jtone,  be- 
caufe  it  may  be  cut  eafily  in  all  directions. 

6.  Klllas. 

This  ftone  is  of  a  pale  grey  or  greenifli  co 
lour  ;  either  lamellar,  or  coarfely  granular. 
It  is  found  chiefly  in  Cornwall. 

7.  Toad/lone. 

Dr  Withering,  who  has  given  an  analyfis  of 
this  ftone,  defcribes  it  as  being  of  a  dark 
brownifh  grey  colour,  of  a  granular  texture, 
not  giving  fire  with  fteel,  nor  effervefcing 
with  acids.  It  has  cavities  filled  with  cryftal- 
lifed  fpar,  and  is  fufible  per  fe  in  a  ftrong 
heat.  It  is  found  in  Derbyiliire.  See  TOAD- 
STONE. 

For  the  ceconomical  ufes  of  the  argillaceous 
earths,  fee  the  article  CLAY. 

[The  compounds  of  this  and  other  earths  will 
fall  to  be  mentioned  under  a  fubfequent  divi- 
iion.] 

CLASS  II.     SALTS. 

BY  this  name  thofe  mineral  bodies  are  called  which 

can  be  diflolved  in  water;  and   give  it  a  tafte ;  and 

which  have  the  power,  at  leaft  when  they  are  mixed 

i  with 


[     io9     ] 

with  one  another,  to  form  new  bodies  of  a  folid  and 
angular  ftiape,  when  the  water  in  which  they  are  dif- 
folved  is  diminilhed  to  a  lefs  quantity  than  is  required 
to  keep  them  in  iblution  ;  which  quality  is  called  cry- 
Jlall'tfation. 

In  regard  to  the  principal  known  circ  am  (lances  or 
qualities  of  the  mineral-  falts,  they  are  divided  into 

1.  Acid  falts,  or  mineral  acids. 

2.  Alkaline  falts,  or  mineral  alkalies. 

Order  I,     ACID  SALTS. 

FOR  the  characters,  properties,  and  phenomena  of 
thefe,  fee  the  article  ACID,  and  CHEMISTRY-/^^. 

Till  of  late  no  more  mineral  acids  were  known 
than  the  vitriolic  and  marine ;  the  boracic  or  fedative 
fait  being  reckoned  as  produced  artificially  :  but  later 
difcoveries  have  proved  that  we  may  reckon  at  leaft 
eleven  m'mtral  acids ;  out  of  which  only  two  or  three 
have  been  found  in  an  uncombined  ftate.  Thofe  hi 
therto  known  are  the  following,  viz.  the  vitriolic,  the 
nitrous,  the  marine,  the  fparry,  the  arfenical,  the  rnolyb- 
denic,  the  tvngjlemc,  the  phofphoric,  the  boracic,  the  fuc~ 
cinous,  and  the  aerial,.  See  the  article  ACID,  and 
C  H  E  M  i  s  T  R  y-  Index. 

I.  The  vitriolic  acid.     See  CHEMISTRY-//^*. 

II.  Nitrous  acid. 

This  acid  is  by  fome  excluded  from  the  mineral 
kir^dom,  becaufe  they  fuppofe  it  to  be  pro 
duced  from  putrefaction  of  organic  bodies.  But 
thefe  bodies,  when  deprived  of  life,  are  again  re 
ceived  amongft  foffils,  from  whence  their  more 
fixed  parts  were  originally  derived.  For  the  na^» 
ture  of  this  acid,  See  CHEMISTRY-/^;*, 

III.  Acid  of  common  or  fea-falt.     See  CHEMISTRY- 
Index,  at  Acid  and  Marine. 

IV.  The  Jiuor  acid,  or  fparry  fluor  acid.     See  CHE- 

L  This 


This  acid  is  obtained  by  art,  as  it  has  never  been 
found  difengaged,  but  united  to  calcareous  earth, 
forming  a  fparry  fluor,  called  Derbyjlire  Jttior, 
Cornifbjftuor)  blue  jfohn,  or  amcthyjl  root,  when  of  a 
purple  colour.  See  p.  72.  col.  2.  concerning  the 
fubitances  arifing  from  the  combination  of  this 
acid  with  calcareous  earth* 

V.  The  acid  of  arfenic.     See  CHEMISTRY-//^/*?*. 

VI.  The  acid  of  molybdena.     Ibid. 

VII.  The  acid  vitungjlcn.     Ibid. 

VIII.  The  phofphork  acid.     Ibid. 

IX.  The  loracic  acid.     Ibid. 

X.  The  fuccinous  or  amber  acid.     Ibid. 
XL     Aerial  acid,  orfaedair.     Ibid. 

Order  II.     ALKALINE  MINERAL  SALTS. 

FOR  the  characters,  properties,  and  phenomena  of 
thefe,  fee  the  article  ALKALI;  alfo  CHEMISRTY-//W&JC, 
at  AlMy  Alkalies. 

New  acids  are  daily  detected  :  but  no  additions  have 
been  made  to  the  three  fpecies  of  alkali  long  fince  known. 

Thefe  alkali  falts  are, 
I.  Vegetable  fixed  alkali  (A.) 


(A)  With  regard  to  the  origin  ot'  the  vegetable  fixed 
alkali,  there  are  fnfficient  proofs  that  it  exifts  already 
formed  in  plants,  and  alfo  that  a  portion  is  if  rmed  by 
combuflion  :  but  in  each  cafe,  the  alkali  is  obtained  in 
an  impure  (late,  through  the  admixture  of  other  mat 
ters,  which  mull  be  feparated  before  it  can  be  ufed  for 
chemical  purpofes. 

The  ctiidres  gra velees  are  made  by  burning  the  hulks 
of  grapes  and  wine  lees.  They  contain  the  pureft  alka 
li  met  with  in  common,  and  are  ufed  by  the  dyers. 

Pot-afh  is  made  by  burning  wood  and  other  veget> 
ables.  This  alkali  is  much  phlogifticated,  and  con 
tains 


[  III  ] 

Vegetable  fixed  alkali,  deprived  of  every  acid, 
is  not  found  any  where  by  itfelf ;  but  it  is  fome- 
times  met  with  in  combination  with  the  vitriolic 
acid  or  the  muriatic,  generally  with  the  nittous, 
rarely  with  the  aerial  (B.) 

The  fixed  vegetable  alkali  (or potciffe  of  Morveau), 
is  of  a  powdery  appearance,  and  of  a  dead  white 
colour.  When  pure,  it  is  much  more  cauftic 
than  the  neutral  fait ;  it  forms  with  the  aerial 
acid,  and  even  corrodes  the  (kin  (c.) 


tains  many  foreign  and  faline  matters,  which,  however* 
niay.befeparated. 

That  which  is  obtained  from  the  afhes  of  wood 
burned  in  kitchens  is  the  moft  pure  of  all.  On  the  con 
trary,  that  which  is  got  from  tartar,  properly  burned, 
then  diflblvecl  in  boiling  water,  and  purified  by  filtra 
tion  and  cryftallifation,  is  called  ^/f  of  water.  It  is  the. 
bcft. 

(B)  The  vegetable  alkali  is  feldom  found  in  the 
enrth,  except  in  wells  of  towns,  as  at  Doway,  or  in  the 
argillaceous  alum-ore  of  la  Tolfa :  it  is  found  alfo  unit 
ed  to  the  nitrous  acid,  near  the  furface  of  the  earth,  in 
Spain,  and  in  the  Eaft-Indies,  probably  from  the  putre 
faction  of  vegetables. 

(c)  Common  vegetable  alkali,  fait  of  tartar,  and 
pot-aih,  were  formerly  confidered  by  chemifts  as  fimple 
alkalis ;  but  Dr  Black  has  demonftrated  them:  to  be 
true  neutral  falts,  arifmg  from  the  combination  of 
the  vegetable  alkali  with  the  aerial  acid,  From  hence 
it  follows,  that  the  above  common  alkalies,  even  after 
any  other  extraneous  fubftance  has  been  extracted, 
muft  be  freed  from  this  acid,  by  putting  each  in  a 
crucible,  and  expofmg  it  to  a  ftrong  fire,  which  will 
didipate  this  aerial  acid.  The  alkali  fo  purified,  is  to 
be  put  in  a  glafs  vial  before  it  be  entirely  cold,  and 
kept  clofev?ith  a  proper  (lopple;  othervvife  the  aerial 
L  z  acid 


C    n2    J 

1.  It  changes  the  blue  colours  of  vegetables  into  a 
deep  green. 

2.  It  has  no  fmell  when  dry ;  but  when  wetted,  it 
has  a  flight  lixivious  odour. 

3.  Its  tafte  is  ftrongly  acrid,  burning,  cauftic,  and 
urinous  (D).     This  latt  fenfation  arifes  from  the 
volatile  alkali  it  difengagesfrorn  animal  fub (lances. 

4.  When  expofed  to   the  air,  it   attracts  humidity, 
and  is   reduced  into  a  tranfparent  colourlefs  li 
quor.     According    to  Gellert,  it  attracts  three 
times  its  own  weight  of  water. 

5.  It    likewife    attracts    fometimes  the  aerial  acid 
from  the  atmofphere,  and  is  thereby  deprived  of 
its  property  of  deliquefcing. 

6.  When  it  is  diflfolved  in  an  equal  weight  of  wa 
ter,  it  has  an  oily  feel,  owing  to  its  action  oa  the 
fatty  parts  of  the  fkin,  whence  it  is,  though  im 
properly,  called  oil  of  tartar. 

-.  In  a  moderate  heat  it  melts  ;  but  in  a  more  vio 
lent  fire,  it  is  difperfed  or  volatilifed. 

8.  It  is  a  moil  powerful  folvent  by   the  dry  way : 
in  a  proper  heat,  it  diflblves  calcareous,  argilla 
ceous,  filiceous,  and  metallic  earths :  and  when 
the  alkali  is  nearly  equal  in  quantity  to  the  earth, 
it  forms  various  kinds  of  hard,  folid,  and  tranf 
parent  glafs. 

9.  But   if  the  alkali  be  in  quantity  three  or  four 
times    that    of  the  earth,  the  glafs  is  deliquef- 
cent. 


acid  which  floats  in  large  quantities  on  the  atmofphere 
will  combine  again  with  the  pure  alkali.   ( Mongez.) 

(D)  The  alkali  muft  ba  largely  diluted  with  water, 
in  order  to  be  tafted  ;  otherwife  it  will  act  on  the 
tongue,  and  corrode  the  parts  where  it  touches.  (Mac- 
quer.) 

10,  Tht 


C     "3     I 

10.  The  mild  vegetable  alkali  unites  with  the  vi 
triolic  acid  with  a  violent  effervefcence,  and  pro 
duces  vitriolated  tartar. 

11.  With  the  nitrous  acid,  it  forms  the  cryftalli- 
fable  fait,  called  nitre. 

12.  With  the  marine  acid  it  forms  a  kind  of  faltlefs 
grateful  than  common  fait,  which  is  called  the 

febrifuge  fait  of  fyhius.  . 

13.  With  vinegar  it  forms  a  neutral  deliquefcent 
fait  of  a  {harp  tafte,  called  terra  foliata  tartari. 

14.  With  cream  of  tartar  it  forms  tartarized  tartar. 

15.  It  diffolves  fulphur,  and  forms  the  fubftance 
called  livsr  of  fulphur ,  winch  is  a  powerful  folvent 
cf  metallic  fubftances. 

1 6.  It  attracts  the  metals,  and  diffolves  fome  of 
them  with   peculiar  management.      Silver,  mer 
cury,  and  lead,  are  more  difficultly  diffolved  than 
gold,    platina,  tin,  copper,  and  efpecially  iron. 
The  lad  gives  a  line  reddiili  faffron  colour,  fir  ft 
obferved  by  Stahl,  who  called  it  the  martial  al 
kaline  tincture* 

17.  It  diffolves  in  the  dry  way  all  the  dephlogifti- 
cated  metallic  calces. 

1 3.  It  unites   with  oils  and  other  fat   fubftances,. 
with  which  it  forms  foap. 

19.  This  alkali  becomes  opaque  when  expofed  to 
the  flame  of  the  blow-pipe :  it  decrepitates  a 
long  time,  and  forms  a  glaffy  button,  which  is 
permanent  in  the  little  fpoon ;  but  is  abfoib- 
ed  with  fome  nolle  on  the  charcoal  when  blown 
upon  it. 
II.  Foffile  fixed  alkalis. 

A.  Alkali  ofthefea,  or  of  common  fait  (E.) 


(E)   This  fait  is  not  met  with  pure  in  Europe ;  but 

it  is  faid  to  be  found  in  both  the  Indies,  not  only  in 

great  quantity,  but  likewife  cf  a  tolerable  purity:  it  is 

L  3  there 


L    »4    3 

i.  Pure. 

This  has  nearly  the  fame  qualities  with  the 
lixivious  fait,  which  is  prepared  from  the  allies 
of  burnt  vegetables.  It  is  the  fame  with  the 
fal  fod<z,  or  kelp :  for  the  kelp  is  nothing 
elfe  than  the  allies  remaining,,  after  the  burn 
ing  of  certain  herbs  that  abound  in  common 
fait ;  but  which  common  fait,  during  the 
burning  of  thofe  vegetables,  has  loft  its  acid 
(F). 

The  properties  of  the  foffile  alkali  are  as 
follows : 


there  collected  in  form  of  an  efflorefcence  in  the  ex- 
teniive  deferts,  a  profitable  trade  being  carried  on  in 
it  for  the  making  of  foap  and  glafs  ;  and,  therefore,  it 
is  very  probable  that  the  ancients  meant  this  fait  by 
their  natron  or  bavrack.  (Magellan.) 

(F)  The  mineral  alkali  is  often  combined  with 
the  vitriolic  and  marine  acid,  alfo  with  the  aerial 
acid  ;  with  which  laft  it  retains  not  only  the  name  but 
many  of  the  properties  of  a  pure  alkali,  becaule  this 
lail  acid  is  eafily  expelled. 

It  is  eafily  known  by  its  cryftallifation  and  its  folu- 
bility  in  two  times  and  an  half  of  its  weight  of  water, 
at  the  temperature  of  60  degrees. 

One  hundred  parts  of  this  alkali,  when  pure  and  re 
cently  cryftallifed,  contain  20  of  mere  alkali,  16  of 
aerial  acid,  and  64  of  water.  (Mccquer.) 

Mineral  alkali  is  found  in  Hungary,  in  marfhy 
grounds,  of  an  argillaceous  or  marly  nature,  either 
mixed  with  water  or  cryfiallifed  and  efflcrefcing.  It 
is  found  alfo  in  Egypt  at  the  bottom  of  lakes,  and  dried 
up  by  the  rummer's  heat ;  and  alfo  in  the  province  of 
Surhena,  28  days  journey  from  Tripoli,  where  it  has 
the  name  of  Trona  ;  in  Syria,  Perfia,  as  well  as  in  the 
Eaft-Indies,  and  China,  where  it  is  called  kien.  It  fonie- 

times 


['   "5    ] 

1.  It    effervefces  with  acids,    and   unites    with 
them. 

2.  Turns  the  fyrup  of  violets  to  a  green  colour. 

3.  Precipitates  fnblimate  mercury  in  an  orange- 
coloured  powder. 

4.  Unites  with  fat  fubftances,  and  forms  foap. 

5.  DifTolves  the  nliceous  earth  in  the  fire,  and 
makes  glafs  with  it,  &c.     It   diftinguifhes  it- 
felf  from  the   fait  of  the  pot-aihes  by  the  fol 
lowing  properties  (G). 

6.  It    ihoots    eaiily  into  rhomboidal   cryftals ; 
which 

7.  Fall  to  powder  in  the  air,  merely  by  the  lofs 
of  their  humidity  (H). 


times  germinates  on  walls,  and  is  called  by  many 
apbronitron.  In  its  native  ftate,  it  is  frequently  mixed 
with  magnefian  earth,  common  fait,  muriatic  magne- 
fia,  and  marine  felenite.  ( Kirwan.) 

(G)  This  mineral  alkali  likewife  differs  from  the 
vegetable,  I.  By  its  tafte,  which  is  lefs  corrofive  and 
burning.  2.  By  its  not  deliquefcing.  3.  By  the  fmall 
degree  of  heat  it  produces  if  calcined,  and  afterwards 
added  to  water.  4.  By  its  property  of  cryftallifing,  by 
evaporating  the  water  from  its  folution,  as  i«  praclifed 
with  neutral  falts  ;  whereas  the  vegetable  alkali  does 
not  cryftallife  unlefs  combined  with  a  large  portion  of 
aerial  acid. 

(  H  )  This  alkali  being  a  very  ufeful  commodity,  and 
eflentially  neceflary  in  a  number  of  manufactories, 
many  ingenious  procefTes  have  been  contrived  and 
attempted  to  procure  it  at  a  cheap  rate,  by  decora- 
poiing  the  fea-falt  ;  but  it  is  believed,  that  till  lately 
none  of  thefe  new  manufactures  have  fucceeded,  ex 
cept  that  of  Mr  Turner,  mentioned  by  Mr  Kir  wan  in 
the  fecond  part  of  the  Philofophical,  Tranfactions  for 

1782. 


C    "6    3 

S.  Mixed  with  the  vitriolic  acid,  it  makes  the 
fal  mirahile  Glauberi. 

9.  It  melts  more  eafily,  and  is  fitter  for  produ 
cing  the  fal   commune    regeneratum,    nit  rum    cu< 
licum  &c.     Perhaps  it  is  alfo  more   conveni 
ently  applied  in  the  preparation  of  feveral  me 
dicines. 

10.  It  is  fomewhat  volatile  in  the  fire. 
III.     Volatile  mineral  alkali. 

This  perfectly  refembles  that  fait  which  is  extrac 
ted  from  animals  and  vegetables,  under  the  name 
of  alkali  volatile  or  fal  urinofum,  and  is  com 
monly  conftdered  as  not  belonging  to  the  mine 
ral  kingdom ;  but  fmce  it  is  difcovered,  not  only 
in  moft  part  of  the  clays,  but  likewife  in  the  fub- 
limations  at  Solfatara,  near  Naples,  it  cannot  pof- 

fibly 


1/782. The  procefs  is  faid  to  confift  in  mixing  a> 

quantity  of  litharge  with  half  its  weight  of  common 
fait,  which,  on  being  triturated  with  water  till  it 
affumes  a  white  colour,  is  left  to  ftand  fome  hours ;. 
after  which,  a  decompofition  enfues,  the  alkali  being 
left  alone,  whilft  the  acid  unites  to  the  metallic  calx  ; 
and  this  laft  being  urged  by  a  proper  degree  of  fire* 
produces  a  fine  pigment  of  a  greenifli  yellow  colour, 
\vhofe  fale  pays  for  the  moft  part  of  the  expences. 

'Mr  Kirwan  fays,  in  the  place  already  quoted,  that 
if  common  fait  perfectly  dry  be  projected  on  lead 
heated  to  iacandefcence*  the  common  fait  will  be  de- 
compofed,  and  a  horn-lead  formed,  according  to  Mar- 
graaf.  He  adds  alfo,  that  according  to  Scheele,  if  a 
iblution  of  common  fait  be  digefted  with  litharge,  the 
common  fait,  will  be  decompofed,  and  a  cauitic  alkali 
produced ;  and  finally,  that  Mr  Scheele  decompofed 
common  fait  by  letting  its  folution  flowly  pals  thro' 
a  funnel  filled  with  litharge. 


C    117    ] 

fibly  be  quite  excluded  from  the  mineral  king 
dom  ( i). 
Its  principal  qualities  are, 

a.  In  the  fire  it  rifes  in  forma  fieca>  and  volati- 
lifes  in  the  air  in  form  of  corrofive  vapours, 
which  are  ofFenfive  to  the  eyes  and  nofe  (K). 


(i)  It  is  eafily  known,  by  its  fmell,  though  in  a 
mild  ftate,  by  its  volatility,  and  by  its  action  on  cop 
per;  the  folutions  of  which,  in  the  mineral  acids,  are 
turned  blue  by  an  addition  of  this  alkali.  It  is  fre 
quently  found,  though  in  fmall  quantities,  in  mould, 
marie,  clay,  fchiftus,  and  in  fome  mineral  waters.  It 
probably  derives  its  origin  in  the  mineral  kingdom, 
from  the  putrefaction  or  combuftion  of  animal  or  ve 
getable  fubftances.  (Kirivan.) 

The  fame  is  cauftic  when  uncombined  with  aay  acid, 
not  excepting  even  the  aerial  acid.  It  differs  from  the 
other  two  alkalies  in  many  effential  particulars,  i* 
By  its  aeriform  or  gafeous  nature.  For  the  volatile 
alkali,  in  a  ftate  of  purity,  is  nothing  more  than  an  al 
kaline  gas  difFufed  in  water,  as  Dr  Prieftley  has  de- 
monftrated.  2.  By  its  volatility.  3.  By  the  nature 
of  the  falts  it  forms  with  acids,  which  are  very  different 
from  thofe  whofe  bafes  are  formed  either  of  the  veget 
able  or  mineral  alkali.  ( Monge-z.) 

(K)  Pure  volatile  alkali,  in  an  aerial  form,  refem- 
bles  atmofpheric  air,  but  is  more  heavy.  Its  fmell  is 
p;-ntetrating,  and  fuffocates  animals.  Its  tafte  is  acrid 
and  cauftic.  It  quickly  converts  blue  vegetable  co 
lours  to  green,  and  produces  heat  during  its  combi 
nation  with  water.  But  if  the  wat?r  be  frozen,  it 
melts,  producing  at  the  fame  time  an  extreme  degree 
of  cold.  It  has  a  remarkable  action  on  moil  metals, 
particularly  copper. 

This  fubftance  is  obtained  by  the  putrefactive  fer 
mentation  from  animal  and  fome  vegetable  matters. 

It 


£.  It  precipitates  the  folution  of  the  mercurial 

fublimate  in  a  white-powder. 
f.  Italfo  precipitates  gold  out  of  aqua-regia,  and 

detonates  with  it ;  becaufe, 
d.  It  has  a  re-ac~Hon  in  regard  to  the  acids,  tho* 

not  fo  ftrongly  as  other  alkalies, 
f.  It  tinges  the  folution  of  copper  blue,  and  dif* 

folves  this  metal  afreiH  if  a  great  quantity  is 

added  (L). 
f.  It  deflagrates  with  nitre,  which  proves  that  it 

contains  a  phlogifton. 
It  is  never  found  pure. 

Order  III.     NEUTRAL  SALTS. 

ACIDS  united  to  alkalies  form  neutral  falls.  Thefs 
difTolved  in  water  are  no  ways  difturbed  by  the  addi 
tion  of  an  alkali ;  and  generally,  by  evaporation,  con 
crete  into  cryftals.  If,  by  proper  tefts,  they  fhow 
neither  acid  nor  alkaline  properties,  they  are  faid  to  be 
neutrals ;  but  imperfeO9  when,  from  defect  in. 

quantity 


It  is  this  fait  which  caufes  that  ftrong  fmell  which 
is  perceived  in  drains  and  privies  on  a  change  of 
weather.  (Monger)* 

Its  volatility  arifes  from  a  very  fublile  and  volatile 
(or  phlogiftic)  oil,  which  enters  as  a  principle  into  its 
compofition.  (Macquer). 

(L)  The  folution  of  copper  by  this  alkali,  which  is 
of  a  fine  blue,  prefents  a  remarkable  phenomenon. 
For  if  it  be  kept  in  a  well  clofed  phial,  the  colour  de 
cays,  and  at  length  difappears,  giving  place  to  tran- 
fparency.  But  on  opening  the  phial,  the  furface  or 
part  in  contact  with  the  air  becomes  blue,  and  the 
colour  is  communicated  through  the  whole  mafs. 
This  experiment  may  be  many  times  repeated  with 
the  fame  fuccefs. 


-quantity  or  flrength  of  one  ingredient,  the  peculiar 
properties  of  the  other  more  or  lefs  prevail. 

I.  Vitriolated  tartar,  vitriolated  vegetable  alkali,  or 

(as  Morveau  calls  it)  the  vitriol  of  pot-ajh. 

This  is  a  perfectly  neutral  fait,  which  remits  from 
the  combination  of  the  vitriolic  acid  with  the  ve 
getable  fixed  alkali.  According  to  Bergman,  it 
feldom  occurs  fpontaneouily  in  nature,  unlefs 
where  tracks  of  wood  have  been  burnt  down  :  and 
Mr  Bowles,  quoted  by  Mr  Kirwan,  fays  it  is  con 
tained  in  fome  earths  in  Spain.  See  CHEMJSTRY- 
Index. 

It  is  eafily  obtained,  by  pouring  the  vitriolic  acid 
on  a  folution  of  fixed  vegetable  alkali  till  it  is  fa- 
turated.  Cryitals  of  this  neutral  fait  are  then 
formed.  This  cryftallifation  fucceeds  better  by 
evaporation  than  by  cooling,  according  to  Mon~ 
gez. 

The  tafte  of  this  fait  is  difagreeable,  though  fome- 
what  refembling  common  fait. 

II.  Common  nitre,   (Alkali  vegetalile  nltratum). 

This  is  known  in  commerce  by  the  name  of  falt-petre^ 
and  is  alfo  calkd  prifmatlc  nitre,  to  diftinguifh  it 
from  the  cubic  nitre  after-mentioned. — It  is  per 
fect  neutral  fait ;  refulting  from  the  combina 
tion  of  the  nitrous  acid  with  the  pure  vegetable 
alkali. 

According  to  Bergman,  it  is  formed  upon  the  fur- 
face  of  the  earth,  where  vegetables,  efpecially 
when  mixed  with  animal-fubitances,  putrify. — 
See  CH EMI STR ¥-/«</«?#,  at  Nitre. 

III.  Digeftive   fait,  fait   of  Sylvius,  (Alkali  vegetable 
fal.tum). 

This  neutral  fait  is  fometimes,  though  rarely,  met 
with  on  the  earth,  generated  perhaps,  as  profef- 
for  Bergman  ©bferves,  by  the  deftruclion  of  ani 
mal  and  vegetable  fubftances. 

According 


[       12©       ] 

According  to  Macquer,  this  {alt  has  been  very 
wrongly  called  regenerated  marine  fait ;  and  the 
epithet  offe&rifuge  has  alfo  been  given  to  it,  with 
out  any  good  reafon,  to  evince  that  it  has  fuch  a 
property.  But  M.  d«  Morveau  calls  it  muriate  de 
potaffe  with  great  propriety. 

This  fait  is  produced  by  a  perfect  combination  of  the 
vegetable  alkali  with  marine  acid.  It  has  been 
wrongly  confounded  with  common  fait. — It  is 
found  in  fome  bogs  in  Picardy,  and  in  fome  mi 
neral  waters  at  Normandy,  according  to  Monet, 
quoted  by  Kir  wan.  Mongez  adds  alfo  the  fea- 
water,  as  containing  this  fait,  and  that  it  is  ne 
ver  found  in  large  quantities,  although  its  com 
ponent  parts  are  abundantly  produced  by  nature. 
See  CHEMISTRY-/«£/<W,  at  Digejlive. 
IV.  Mild  vegetable  alkali,  (aJkali  vegetable  aeratum.) 

This  fait  was  formerly  confidered  as  a  pure  alkali, 
known  by  the  name  of  poiafn  and  fait  of  tartar  ,• 
but  fince  the  difcovery  of  the  aerial  acid,  it  is  ve 
ry  properly  claffed  among  the  neutral  falts,  and 
ought  to  be  called  aerated  potaffe. 

It  refults  from  a  combination  ot  the  vegetable  alkali 
with  theaeiial  acid,  and  is  hardly  ever  found  na 
tive,  unlefs  in  the  neighbourhood  of  woods  de- 
flroyed  by  fire. 

On  being  expofed  on  a  piece  of  charcoal,  urged  by 
the  blow-pipe,  it  melts,  and  is  abforbed  by  the 
coal ;  but, 

In  the  metallic  fpoon,  it  forms  a  glaify  bead,  which 
becomes  opaque  when  cold. 

V.  Vitriolated  acid  faturated  with  mineral  alkali  ; 
Glauber's  fait.  Alkali  mmerale  vltriolatum. 

This  is  a  neutral  fait,  prepared  by  nature  (as  well ! 
as  by  art),  containing  more  or  lefs  of  iron,  or  of 
a  calcareous  earth  ;  from  which  arifes  alfo  fome 
difference  in  in  its  effe&s  when  internally  ufed. 
It  ftiocts  cafily  into  prifmatical  cryftals,  which 

become 


ii 


C       121       ] 

become  larger  in  proportion  to  tlie  quantity  cf 
water  evaporated  before  the  cryftallifation. 
When  laid  on  a  piece  of  burning  charcoal,  or 
elfe  burnt  with  a  phlogiftrn,  the  vitriolic  acid  dif- 
covers  itfelf  by  the  imell  refembling  the  hepar 
fulphuris. 

It  is  found  in  a  diifolved  ft  ate  in  fprings  and 
wells.  Some  of  the  lakes  in  Siberia  and  At^rd- 
can,  and  many  fprings  in  other  places,  contain 
this  fait,  according  to  Bergman.  It  is  found 
in  the  fea-water;  a!fo  in  the  earth,  at  feveral 
parts  of  Dauphine  in  France,  and  in  Lorraine  ; 
and  fometimes  it  germ.inates  on  the  furface  of  the 
earth,  according  to  Monet,  quoted  by  Kirwan. 
It  is  found,  in  a  dry  form,  en  walls,  in  iiich  places 
where  aphronitrum  has  efHorefced  through  them, 
and  the  vitriolic  acid  has  happened  to  be  pre- 
fent ;  for  inilance,  where  marcafites  are  roa/led 
in  the  open  air.  This  fait  is  often  confounded 
with  the  aphronitrum  or  mild  mineral  alkali. 

VI.  Cubic  or  quadrangular  nitre.     Alltc.li  minerals  «/- 
f reft  am. 

This  is  the  neutral  fait  which  refults  from  the 
combination  of  mineral  alkali  with  nitrous  acid. 
It  has  almoit  all  the  characters  of  prifmatic  or 
common  nitre,  from  which  it  only  differs  on  ac 
count  of  its  bafe ;  and  takes  its  denomination 
from  the  figure  of  its  cry  Pails,  which  appear  cu 
bic. 

This  fait  rarely  occurs  but  where  marine  plants 
putrify.  According  to  Bowles,  quoted  by  Kir- 
wan,  it  is  found  native  in  Spain.  See  CHEMISTRY* 
n°74i,  &c. 

VII.  Common  fait,  or  fea-falt ;  Alkali  minerals  falitum, 
fal  commune. 

This  fait   flioots  into    cubical  cryftals  during  the 
very  evaporation  ;  crackles  in  the  fire,  and  at 
tracts  the  humidity  of  the  air.     It  is  a  perfectly 
M  neutral 


C    i«    3 

Central  fait,  compofed  of  marine  acid,  faturated 
with  mineral  alkali.  It  lias  a  faline  but  agree 
able  flavour.  See  CHEMIST&Y-//U/IX,  at  Sea- 
fait. 

A.   Rock  fait,  foffile  fait ;  Sal  montanum.     Occurs 
in  the  form  of  folid  ilrata  in  the  earth. 
j.  With  fcaly  and  irregular  particles. 
a.  Grey,  and 

I..  White.     Thefe  are  the  mod  common,  but 
the  following  are  fcarcer : 

c.  Red; 

d.  Blue  ;  and 

e.  Yellow,  from  Cracow  in  Poland,  England, 
Salzberg,  and  Tirol. 

2.  Cryftallized  rock  fait ;  fal g^mma. 

a.   Tranfparent,   from    Cracow  in  Poland, 

and  from  Tranfylvania. 
JS.  Sea-falt. 

This  is  produced  alfo  from  fea-water,  or  from 
the  water  of  fait  lakes  by  evaporation  in  the  fun, 
or  by  boiling. 

The  feas  contain  this  fait,  though  more  or  lefs 
in  different  parts.     In  Siberia  and  Tartary  there 
are  lakes  that  contain  great  quantities  of  it. 
C.  Spring  fea-faU. 

This  is  produced  by  boiling  the  water  of  the 
fountains    near    Halle    in  Germany,   and  other 
places. 

Near  the  city  of  Lidkoping,  in  the  province  of 
Wcftergotland,  and    in    the    province    of    Dal, 
falt-fprings    are   found,    but    they  contain  very 
little  fait :  and  fuch  weak  water  is  called  folsn  by 
the  Swedes. 
VIII.  Borax. 

This  is  a  peculiar  alkaline  fait,  which  is  fup- 
pofed   to   belong  to  the  mineral  kingdom,  and 
cannot   be    otherwife   defcribed,  than  that  it  is 
......  diilbluble   in    water,  and  vitrefcible  ; 

......  that  it  is  fixed  in  the  fire ;  and  melts 

to 


C     »3     H 

to  a  glafs  ;  which  glafs  is  afterwards  dtflbluble  ia 
water.     See  the  detached  article  BORAX. 
IX.   Mild  mineral  alkali ;  Alkali  miner  ale  aeratum.     Na 
tron,  the  nitre  of  the  ancients. 

This  neutral  fait  is  a  combination  of  the  mine 
ral  alkali  with  the  aerial  acid  or  fixed  air.  It  is 
found  plentifully  in  many  places,  particularly  in 
Africa  and  Afia,  either  concreted  into  cryila1- 
lized  tlrata,  or  fallen  to  a  powder  ;  or  erilorcfcing 
on  old  brick  w.ills  ;  or  laftly,  diifolved  in  fprings. 
It  frequently  originates  from  decompofed  com 
mon  fait. 

This  is  an  imperfeft  neutral  fait,  and  was  for 
merly  confidered  as  a  pure  alkali ;  but  the  difco- 
very  of  the  aerial  acid  has  fhown  the  miilake. 

1.  It  has  nearly  all  the  properties  of  the  pure 
mineral  alkali  N°  II.  A.  i.  (p.  90.),  but  with 
lefs  energy. 

2.  The  vegetable  blue  colours  are  turned  green 
by  this  fait;  k  efflorefces  with  acid;,   and 
has  an  urinous  tafte. 

3.  It  is  foluble  in  twice  its  weight  of  cold  wa 
ter  ;  but  if  the  water  is  hot,  an  equal  weight 
is  fufticient  for  its  folution. 

4p  It  efflorefces  when  expofed  to  the  action  of 
the  atmofphere. 

5.  It  fufes  eafily  on-  the  fire,  but  without  being 
decompofed. 

6.  Facilitates  the  fufion  of  vitrifiable  earths, 
and  produces  glafs  more  or  lefs  fine  accprd- 
ing  to  their  qualities. 

7.  It  is  decompofable  by  lime  and  ponderous 
earth,  which  attract  the  aerial  acid. 

8.  And  alfo  by  the  mineral  acids ,  but  thefo 
expel  the  aerial  acid  of  this  fait,  by  feizing 
its  alkaline  bafis,  (Monger.) 

Wallerius    confounds    this    fait    with  the    apljroni- 

trum  after-mentioned,  and  calls  it  /jalinitritKt,'Vfhcn 

M  2  k 


t     1*4     ] 

Jt  contains  fome  phlogifton.  Mr  Kulbel,  quoted 
by  Wallerius,  lliowed  that  it  exifls  in  fome  vege 
table  earths,  and  takes  it  to  be  the  caufe  cf  their 
fertility;  but  this  (M.  Magellan  obferves)  can 
only  be  on  account  of  its  combination  with  the 
oily  parts  of  them,  and  forming  a  kind  of  foap, 
which  is  mifcible  with  the  watery  juices. 
X.  Vitriolic  ammoniac,  (Alkali  volatile  vitrio'atum.) 

This  neutral  fait  was  called  ficret  fait  of  Glauber, 
and  is  a  combination  of  the  volatile  alkali  with 
vitriolic  acid.  According  to  Bergman,  it  is 
fcarcely  found  any  where  but  in  places  where  the 
phlogifiicatcd  fumes  of  vitriolic  acid  arife  from 
burning  fulphur,  and  are  abforbed  in  putrid  places 
by  the  volatile  alkali.  Thus  at  Fahlun  the  acid 
vapour  from  the  roaded  minerals  produces  this 
fait  in  the  neceirary-houfes.  Dr  Withering,  how 
ever,  obferves,  that  as  volatile  alkali  may  be  ob 
tained  in  large  quantities  from  pit-coal,  and  pro 
duced  by  procefles  not  dependent  upon  putrefac 
tion,  there  is  reafon  to  believe  that  the  vitriolic 
nmmoniac  may  be  formed  in  feveral  ways  not  no 
ticed  by  the  above  author. 

It  is  faid  to  have  been  found  in  the  neighbour 
hood  of  volcanoes,  particularly  of  Mount  Vefu- 
vius,  where,  indeed,  it  might  well  be  expecled  ; 
yet  its  exigence  feems  dubious,  fmcc  Mr  Berg 
man  could  fcarce  find  any  trace  of  it  among  the 
various  Specimens  of  falts  from  Vefuvius  which 
he  examined.  The  reafon  (according  to  M.  Ma 
gellan)  probably  is,  that  the  vitriolic  acid  difen- 
gaged  by  the  combuftion  of  fulphur  is  in  a  phlo- 
gifticated  (late  ;  and  all  its  combinations  in  this 
fcate  are  eatily  decompofed  by  the  marine  acid, 
which  plentifully  occurs  in  volcanoes.  It  is  alfo 
faid  to 'be  found  in  the  mineral  lakes  of  Tufcany, 
which  is  much  more  probable,  as  the  vitriolic  acid 
when  united  to  water  eafily  parts  with  phlogiflon, 

and 


[     125     ] 

and  recovers  its  fuperiority  ever  other  acids.  It 
is  faid  iikewife  that  this  neutral  fait  is  found  on 
the  furface  of  the  earth  in  the  neighbourhood  of 
Turin. 

1.  This  fait  is  of  a  friable  texture,  and  has  an 
acrid  and  urinous  tafte. 

2.  Attracts  themoiihrre  of  the  atmofphere. 

3.  Js  very  foluble  in  water,  it  requiring  only 
twice  its  weight  of  cold  water,  c-r  an  equal 
weight  of  boiling  water,  to  be  cliifolved. 

^..  It  becomes  liquid  on  a  moderate  fire  ;  but  if 
urged, 

5.  It  becomes  red  hot,  and  volatilizes. 

6.  The  nitrous  and  muriatic  acid  decompofc 
this  fait  by  feizing  the  volatile  alkali.      But:. 

7.  Lime,  ponderous  earth,  and  pure  fixed  al 
kali,  fet  the  volatile  alkali  free,  and  combine 
with  the  vitriolic  acid. 

8.  According  to   Kirwan,   100  parts  of  this 
fait  contain  about  42  of  real  vitriolic  acid,. 
40  of  volatile  alkali,  and  18  cf  water. 

This  'vitriolic  ammoniac  is  eafily  known  ;  for  if 
quicklime  or  fixed  alkali  be  thrown  into  its  fo- 
lution,  the  fmell  of  the  volatile  alkali  is  perceived  ; 
and  if  this  folution  be  poured  into  that  cf  ch  il'c 
or  ponderous  earth  by  the  nitrous  acid,  a  precipi 
tate  will  appear. 
XI-  Nitrous  ammoniac,  (Alkali  volatile  niiraiinn.) 

This  is  a  neutral  fait,  waich  rcfuits  from  the  com 
bination  of  the  nitrous  acid  with  the  volatile, 
alkali.  It  is  freomently  fov.nd  in  the  mother-li- 
.quor  of  nitre.  When  mined  wi.h  a  fixed  alkali,, 
the  volatile  betrays  itfelf  by  its  fmell. 

1.  It  is  cf  a  friable  texture,  cf  a  (harp  bitter,, 
nnd  of  a  nitrous  or  cooling  taire. 

2.  According  to  Mongez,  it  attracts  the  moif- 
tirre  of  the  atmosphere;  but  Rome  de  I'Ifle: 
alitrls,  that. its  cryitals  are  net  dcliqucfcent : 

M  3  the. 


the  experiment  may  be  eafily  tried,  and  the- 
truth  afcertained. 

3.  It   is  foluble  in   cold  water ;  but  half  the 
quantity   of  water,   if  boiling,   is    fufficient 
for  dillblving  it. 

4.  It  liquefies  on  the  fire,  and  afterwards  it 
becomes  dry. 

5.  It  detonates  with  a  yellow  flame  before  it 
is  red  hot ;  and  what  is  peculiar  to  this  fait, 
it  needs  not,  like  common  nitre,  the  contact 
of  any  combuftible  matter  for  its  detenation  ;. 
from  whence  it  appears  that  the  volatile  al 
kali  itfelf  poffefTes  a  great  ihare  of  phlogifton. 

6.  Its  component  parts,  viz.   the  nitrous  acid 
and  the  volatile  alkali,  are  not  very  intimate 
ly  united  ;  and  of  courfe, 

7.  It  is  eafily  decompofed  by  all  the  fubflances 
that  have  any  affinity  to  either  of  them. 

8.  Mixed    with  the    muriatic    acid    it  makes- 
aqua  regia. 

9.  One  hundred  parts  of  this  neutral  fait  con 
tain  46  of  nitrous  acid,  40  of  volatile  al 
kali,    and    14    of   water,,  as    Mr    Kirwan 
thinks. 

XII.  Native  fa!  ammoniac.  The  muriatic  (or  marine) 

acid  faturated  with  a  volatile  alkali. 
This  is  of  a  yellowilli  colour,  and  is  fublimed  from 
the  flaming  crevices,  or  fire-fprings,  at  Solfatara> 
near  Naples* 

XIII.  Aerated  <?>r  mild  volatile  alkali* 

This  neutral  fait  rcTults  from  the  combination 
of  volatile  alkali  united  to  the  aerial  acid.  It 
was  formerly  conlidcr-ed  as  a  pure  alkali  : — 
But  the  difcovery  of  the  aerial  acid  (or  fix 
ed  airj  has  fhown  it  to  be  a  true  neutral  fait, 
though  imperfect ;  as  it  retains  ilill  all  the  pro 
perties  of  an  alkali,  though  in  a  weaker  degree,, 
on  account  of  its  combination  with  the  aerial 


r  "7  3 

acid,  which  is  itfelf  the  moft  weak  of  all  acids, 
and  of  courfe  other  ftronger  acids  eafily  diflodge 
it  from  its  bafe,  and  from  various  ammonial  falts. 

1.  This  imperfect  neutral  fait  has  an  urinous 
taile,  and  a  particular  fmell,  which  is  very 
penetrating,  though  lefs  pungent,  than  the 
pure  volatile  r.lkali ;  and  in  the  fame  manner 
it  turns    the  blue    vegetable   juices  green, 
But, 

2.  It  effervefces  with  other  acids  flronger  thaa 
the  aerial  one,  which  the  pure  or  cauftic  vo 
latile  alkali  does  not. 

3.  It  fublimes  very  eafily  with  a  fmall  degree 
of  heat ; 

4.  And  dilfolves  in  twice  its  weight  of  cold 
water ;  but  in  a  lefler  quantity,  when  this 
Lift  is  boiling  hot. 

5.  It  acls  on  metallic  fubdances,  chiefly  on  cop» 
per,  with  which  a  blui  colour  is  produced.. 

According  to  Bcr^m  m,  this  fait  v/as  found  iu 
a  Well  in  London  (Phil.  Trar.f.  for  1767),  at; 
Frankfort  on  the  Main,  and  at  LauchftadtSi — • 
Meifrs.  Hierue,  Henkcl,  and  Brandt,  have- 
found  alfo  this  fall  in,  the  vegetable  eirth,  in  va 
rious  kinds  of  argil,  and  in  f:me  flony  Jubilances... 
Mr  Vozel  found  it  aifo  in  fome  of  the  incrufta- 
tions  at  Gottingcn  ;  and  Mr  Maloain  in  fome 
acidulous  waters  in  France. 

M.  Magellan  obferves,  that  the  borax  and  the 
three  aerated  alkalis  are  called  imperfect  ne  ia\iis  ; 
whillt  the  other  neutral  falts  have  acqr.i--e.l-  the 
name  of  psrfett-,  bccauie  thefe  lail  do  ivot  r-xhihit  :<.  \j 
of  the  diftingtuflimg  properties  of  tlieir  coir.j  o?i  jnt 
parts.  The  three  aer-ited  alkalis  have  a  v  ry  Jilt'ncl: 
alkaline  chamber,  a>  llioy  turn  blue  vejctaole  ju.i  :es 
green,  though  not  of  To  vivid  a  colour  as  the-  cauilic 
alkali-  does ;  and  the  borax  is  capable  oi  icceivin  r  :il- 

mofti 


C     "8     J 

moft  an  equal  quantity  of  its  fedative  acid,  without  lof«- 
fmg  all  its  alkaline  properties. 

In  general,  thofe  neutral  falts,  confiding  of  fixed  al 
kalies  combined  with  acids,  are  more  faturated  than 
thofe  compofed  of  volatile  alkali  called  ammoniacal 
falts,  or  thofe  called  aerated  ;  which  laft  are  only  com 
pofed  by  the  combination  of  the  aerial  acid,  united 
to  any  alkaline  or  earthy  bafe. 

The  aerated  alkalis  are  called  alfo  by  the  name  of 
mild  alkalis,  becaufe  they  poflefs  no  longer  that  fharp 
corroding  quality  which  they  exhibit  when  deprived  of 
the  aerial  acid  or  fixed  air ;  in  which  cafe  they  are 
termed  cauftic  alkalis. 

Thefe  aerated  alkalis  differ  alfo  from  the  cauftic 
ones,  not  only  on  account  of  the  mildnefs  of  their 
tafte,  from  which  comes  their  epithet  of  mild  alkalis, 
but  alfo  by  their  property  of  cryftallifmg,  and  by  their 
effervefcing  with  other  acids,  which  expel  the  aerial 
one,  the  weakeft  of  all  acids  we  know. 

Order  IV.  EARTHY  Neutral  Salts. 

THE  compounds  of  earths  and  acids  which  poflefs 
Solubility  are  decompofed  and  precipitated  by  mild, 
but  not  by  phlogillicated  alkalis. 
I.  Calcareous  earth  combined  with  vitriolic  acid. — 
Vitriolated  calx;   Selenite  ;   Gypfum.     See  p.   72., 

col.  i.fttpra. 

The  gypfum,  or  plafter,  is  not  only  found  dii- 
folved  in  various  waters,  but  alfo  in  many  places 
it  forms  immcnfe  ftrata.  It  is  placed  by  all  mi- 
neralogifts  among  the  earths,  which  it  greatly  re- 
fembles  ;  but  it  rather  belongs  to  the  ialine  fub- 
ftances  of  the  neutral  kind,  as  appears  by  its 
conftituent  parts.  When  burnt,  it  generates  heat 
with  water,  but  in  a  lefs  degree  than  lime  does.. 
Berg.  Sciag.  §  59. 

This  fait  has  a  particular  tafte,  neither  bitter  nor 
aitnngent,  but  earthy,  when  applied  to  the 

tongue  ;• 


C    "9    3 

tongue  ;  and  it  is  owing  to  it  that  fome.  waters, 
chiefly  from  pumps  and  wells,  are  called  hard  wa 
ters,  becaufe  they  lie  heavy  on -the  (lomach. 

It  is.  unalterable  whilft  kept  in  a  dry  place  ;  but 
on  being  expofed  to  a  m  >ift  air,  it  is  much  alter 
ed,  and  fufFers  a  kind  of  decompofition. 

When  expofed  to  fire  fo  as  to  lofe  the  water  of 
its  cryilallifation,  it  aiTumes  a, dead  white  co 
lour  ;  and  it  is  then  what  we  call  plafter  of  Paris  ; 
but  if  the  fire  is  too  flrong,  it  melts  and  vitri 
fies,  after  lofing  the  vitriolic  acid  with  which  it  is 
faturated.  See  GYPSUM. 

The  moft  famous  quarries  of  gypfum  in  Europe, 
are  thofe  of  Montmartre,  near  Paris.  See  Jour 
nal  dc  Phyfique  ;  1 780,  vol.  xvi.  p.  289  and  1782, 
vol.  xix.  p.  173. 

It  is  found  alfo  in  the  vegetable  kingdpm. — Mr 
Model  found  that  the  white  fpots  in  the  root 
of  rhubarb  are  a  fclenkical  or  gypfeous  earth 
(Journal  ds  Phyf.  vol.  vi.  p.  14,) 

What  is  called  foffil  flour  (farlns  foffOe  in 
French),  generally  found  in  the  fiflures  of  rock 
and  gypfeous  mountains,  is  very  different  from 
the  agaricus  mineralis  p.  71.  col.  I.  and  from  the 
lac  lunae,  p.  87.  col.  r.;  as  it  is  a  true  gypfeous 
earth,  already  defcribed  p.  72.  col.  I.  which,  ac 
cording  to  Moagez,  is  of  a  white  and  fhining 
colour,  though  fometimes  it  affiimes  a  reddifh  or 
bluifli  colour,  on  account  of  fome  martial  mix 
ture. 
II.  Nitre  of  lime,  (Calx  nitrata). 

This  earthy  fait  is  fometimes  found  in  water, 
but  very  fparin»ly.  It  is  faid  that  the  chalk  hills 
in  fome  parts  of  France  become  fpontaneoufly 
impregnated  with  nitrous  acid,  which  may  be 
wartied  out,  and  after  a  certain  time  they  will  be 
come  impregnated  with  it  again.  It  is  a  combi 
nation  of  the  nitrous  acid  with  calcareous  earth. 
(Berg.  Sslagr.) 

I.  It 


C    13°    1 

is  It  Is  defiquefcent ;  and  is  foluble  in  twice  Its 
weight  of  cold  water,  or  in  an  equal  weight 
of  boiling  vrater. 

2.  Irs  tafte  is  bitter. 

3.  Is  decompofed  by  fixed  alkalies,  which  form- 
the  cubic  and  the  prifmatic  nitres. 

4.  But  cauftic  volatile  alkali    cannot  deccm- 
pofe  it. 

5.  It  does  not  deflagrate  in  the  fire  ;  yet  paper 
moiftened  with    a    faturated  folution  of  it 
crackles  in  burning. 

6.  In  a  ftrong  heat  it  lofes  its  acid. 

7.  Its  folution  does  not  trouble  that  cffilverin 
nitrous  acid. 

8.  The  vitriolic  acid  precipitates  its  bafis. 

9.  As  does  likewife  the  acid  of  fugar. 

10.  One  hundred  parts  of  it    contain,  when 
well  dried,  about  33  of  nitrous  acid,  32  of 
calcareous  earth,  and  35  of  water. 

It  exifts  in  old  mortar,  and  in  the  mother  li 
quor  of  nitre ;  and  alfo  in  the  chalk  rocks  near 
Roche  Guyon,  in  France.     (Kirni-an.) 
III.   Muriatic  chalk,  or  fixed  fait  ammoniac.     Acidum 
fulls  comtnunis  terra  calcareafaturaium. 

This  fomewhat  deliquefces,  or  attracts  the  humidity 
of  the  air.  It  is  found  in  the  fea  water. 

It  is  with  great  impropriety  that  this  fait  has  ob 
tained  the  name  of  ammoniac,  on  account  only 
of  its  being  formed  in  the  chemical  laboratories 
during  the  decompofition  of  the  ammoniacal  fait 
with  Time,  in  the  procefs  for  making  the  cauftic 
volatile  alkali.  In  this  cafe,  the  muriatic  acid 
unites  to  the  calcareous  bafis,  while  this  la  ft  gives 
its  water  to  the  volatile  alkali ;  \vhich,  therefore, 
comes  over  in  a  fluid  cauftic  ftate :  but  if  chalk 
is  employed  inftead  of  l-'me,  the  volatile  alkali 
receives  the  aerial  acid  inftead  of  water,  and  comes 
ever  in  a  concrete  form.  In  n-either  cafe,  the  new 

combination^ 


f    '3'     3 

combination  of  calcareous  earth  with  mnriatic 
fait  has  any  volatile  alkali  to  deferve  the  name  of 
ammoniac  al  fait.  (  Macquer.) 

1.  This  earthy  fait  has  a  faline  and  very  difa- 
greeable  letter  talte.     It  is  fuppofed  to  be 
the  caufe  of  that  bitternefs  and  naufeous  tafte 
of  fea- water, 

2.  It  fufes  in  the  fire,  and  becomes  phofphoref- 
cent,  after  undergoing  a  ftrong  heat. 

3.  It  becomes  hard,  fo  as  to  (Inkx-  fire  with  fteeL 

4.  It  is  then  the  ph^fphorus  of  Homberg. 

5.  It  is  decompofabie  by  ponderous  earth  and 
fixed  alkalis, 

6.  And  alio  by  the  vitriolic  or  nitrous  acid ; 
which  expel  the  muriatic  acid,  to  unite  with 
the  calcareous  bafis.     (Mongez.) 

7.  Its  folution  renders  that  of  iilv.r  in  the  ni 
trous  acid  turbid,  at  the  fame  time  that 

8.  It  makes  no  change  in  that  of  nitrous  felenite. 

9.  It  obftinately  retains  its  acid  in  a  red  heat. 

10.  One  hundred  parts  of  this  earthy  fait  con 
tain,  when   well  dried,  about  42  of  marine 
acid,  38  of  calcareous  earth,  and  20  of  water. 

11.  It  is  found  in  mineral  waters,  and  in  the 
fait  works  at  Saltzburg.      (Kirwan.) 

IV.  Aerated  chalk,  (Calx  aerata.} 

Whenever  calcareous  earth  is  overfaturated  with 
the  aerial  acid,  it  becomes  a  true  earthy  neutral 
fait ;  becomes  foluble  in  water,  and  has  a  flight 
pungent  bitter  tafte.  It  is  commonly  found  dif- 
folved  in  waters,  in  confequence  of  an  excefs  of 
the  aerial  acid.  When  this  greatly  abounds,  the 
water  is  faid  to  be  hard  (cruda).  By  boiling  or 
by  evaporation,  it  depofits  ftreaks  or  crults  of  cal 
careous  matter. 

But  when  the  calcareous  tarth  is  only  faturated  with 
the  aerial  acid  without  excefs,  it  is  not  eafily  fo 
luble  j  it  is  then  the  calcareous  fpar,  p.  7-1.  co/.  2. 

and 


[     13*     ] 

and  is  properly  referred  to  the  clafs  of  earths, 
p.  71.  col.  i. 

V.  Vitriolated  ponderous   earth.     Terra  pondercfa  vi~ 

triolata  ;  barytes  vitriol  at  a, 

This  earthy  fait,  known  by  the  name  of  ponderous 
fpar,  is  a  combination  of  the  ponderous  earth  def- 
cribed  in  p.  75.  col.  i.  with  the  vitriolic  acid  ;  and 
has  been  already  treated  of. 

The  nitrous  ponderous  earth,  according  to  Berg 
man,  has  not  yet  been  found,  although  it  may 
perhaps  exift  fomewhere,  and  of  courfe  be  difco- 
vered  in  nature. 

VI.  Muriatic  barytes,  marine  baro-felenite.     Barytes 
Jalita* 

This  earthy  fait  confifts  of  marine  acid  united  to  the 
ponderous  earth.  It  is  faid  to  have  been  found 
in  feme  mineral  waters  in  Sweden ;  and  may  be 
known  by  its  eafy  precipitability  with  vitriolic 
acid,  and  by  the  great  insolubility  and  weight  of 
this  refulting  compound,  which  is  the  true  pon 
derous  fpar  of  the  preceding  fection. 

VII.  Aerated  ponderous  earth.     Barytes  aerata. 
This  earthy  neutral  fait   vas  found  by  Dr  Wither 
ing  in  a  mine  at  Alfton-moor  in  the  county  of 
Cumberland  in  England.     He  fays  that  it  is  ve 
ry  pure,  and  in  a  large  mafs.     This  fubftance  is 
anew  acquifition  to  mineralogy,  and  may  be  turn 
ed  to  ufeful  purpofes  in  chemilhy. 

1.  It  efFervefces  with  acids,  and  melts  with  the 
blow-pipe,  though  not  very  readily. 

2.  In  a  melting  furnace,  it  gave  force  figns  of  fu- 
fion  ;  but  did  not  feel  cauftic  when  applied  to 
the  tongue,  nor  had  it  loll  its  property  of  effer- 
vefcing  with  acids. 

3.  But  the  precipitated  earth  from  a  faturated 
foluticn  of  it  in  the  marine  acid,  by  the  mild 
vegetable  or  mineral  alkali  being  burned,  and 
thrown  into  water,  gave  it  the  properties  of 

i  lime- 


[     '33     J 

lime-water,  having  an  acrid  tafte  in  a  high- 
degree  :  and  a  Tingle  drop  of  it  added  to  the  fo- 
lutions  of  vitriolated  falts,  as  the  Glauber's  fait, 
vitriolated  tartar,  vitriolic  ammoniac,  alum, 
Epfom  fait,  felenite,  occafioned  immediately  a 
precipitation  ;  from  whence  it  appears  to  be  the 
niceft  teft  to  difcover  the  vitriolic  acid.  By  if 
the  marine  acid  may  alfo  be  eafily  freed  from 
any  mixture  of  vitriolic  acid,  by  means  of  this 
calx  of  ponderous  earth.  See  CHEMISTRY  n6 
1049.  et.Jeq. 
VIII.  Vitriolated  magnefia. 

This  earthy  neutral  fait  is  called  by  the  Englifhxs^- 
fomfalt ;  Sel  d*  Angleterre  by  the  French,  and  allb 
Jel  de  SedlitZ)  de  Seydfchutz,  fel  amsr,  fel  cathartiqnc 
amer,  &c.  Thefe  various  names  are  given  to  it, 
either  on  account  of  its  properties,  it  being  a  ve 
ry  mild  purgative  ;  or  from  the  places  where  it  is 
found,  befides  many  others*  as  in  the  waters  of 
Egra,  of  Creutzbourg,  Ohernental,  Umea,  &e. 
It  has  alfo  been  round  native,  mixed  with  com 
mon  fait  and  coaly  matter,  germinating  on  fbme 
free  ilones  in  coal  mines.  See  Kirivan's  Minera 
logy,  p.  183. 

1.  It  has  a  very  bitter  taftc. 

2.  It  is  foiuble  in  one  part  and  a  half  of  its  weight 
of  cold  water :  but  in  hot  water,  a  given  wen-he 
of  it  difTolves  the  double  of  this  fait. 

3.  It  cfHorefces  when  expofed  to  a  dry  atmofphere, 
and  is  reduced  to  a  white  powder. 

4.  Expofed  to  the  fire,  it  lofes  the  u  ater  of  its  cry- 
ftallifation,  and  is  reduced  into  a  friable  mais. 

5.  This  eaithy  fait  is  decompofed  by  fixed  and  vo-> 
latile  alkalies. 

6.  Lime-water  precipitates  the  magnefia  from  its 
folution,  the   calcareous  earth  of  lime-water 
combining  itfelf  with  the  vitriolic  actd,  and  for 
ming  a  felenite.     Ar.  £.    By  this  teit  the  vilri- 

N  elated 


c  134  : 

elated  magnefia  is  eafily  diftinguifhcd  from  the 
vitriolated  mineral  alkali  or  Glauber's  fait, 
which  it  refembles. 

7.  Bat  crude  chalk,  or  aerated  calcareous  e~rth, 
has  not  fuch  an  effect  in  the  fame  cafe  ;  which 
fhows  ho\v  much  the  efficacy  of  this  fubftance, 
viz.  the  calcareous  earth,  is  diminifhed  merely 
by  its  union  with  the  aerijl  acid. 

8.  When  urged  by  the  flame  with  the  blow-pipe, 
it  froths  ;  and  may  be  melted  by  being  repeat 
edly  urged  with  that  inftrument. 

9.  With  bcrax  it  eflfervefces,  and  alfo  when  burn 
ed  with  the  micrccofmic  fait. 

10  According  to  Bergman,  100  weight  of  this 
fait  contains  only  19  parts  of  pure  ma^nefia, 
33  of  vitriolic  acid  :  and  48  of  water.  But 

ii.  According  to  Kin-van,  100  parts  of  it  contain 
about  24  of  real  vitriolic  acid,   19  of  magnefi- 
an  earth,  and  57  of  water. 
IX.  Nitrated  magr.efia  ;   nitrous  Enfom  fcilr. 

This  earthy  fait  is  ufually  found  together  with  nitre. 

It  is  a  combination  of  the  nitrous  acid  with  the 

niagnefian  earth. 

1.  It  has  an  acrid  tafle,  very  bitter. 

2.  Attracts  the  motiuire  from  the  atmofphere, 
and  deliquefces. 

3.  Is  very  foluble  in  water. 

4.  Is  eafily  decompo&ble  by  fire. 

5.  The  ponderous  and  calcareous  earths  deccm- 
pole  it,  and  alfo  the  alkalies. 

6.  On  being  urged  by  the  blow-pipe,  it  fwells  up 
with  fome  noife,  but  does  not  detonate. 

7.  If  faturated  folutions  of  nitrous  felenite  and 
of  this  fak  be  mixed,  a  precipitate  will  appear  ; 
but, 

8.  Neither  vitriolic  acid,  ncr  mild  magnefia,  will 
^ccaflon  any  turlidnefs  in  its  folution. 

c.  One 


[     *  35     ] 

9.  One  hundred  parts  of  this  fait  contain  about. 

36  of  real  nitrous  acid,   27  of  magnefian  earth, 

ar.d  37  of  water. 

It  exifts  in  old  mortar,  and  is  found  alfo  in  the 
mother  liquor  of  nitre.  As  lime-water  decorn- 
pofes  it,  M.  da  Morveau  has  indicated  the  ufe  ci" 
this  procefs,  not  only  to  complete  its  analyils  ; 
bat  alfo  to  feparate,  in  large  quantities,  and  at 
a  very  cheap  rate,  the  magnefian  from  the  calc  •> 
reous  earth,  as  M.  Mongez  relates  upon  this  fub- 
jed. 
'X.  Muriatic  magnefia.  Magne/iafallta. 

This  earthy  fait  is  a  combination  of  magnefian  earth 
with  the  muriatic  acid.  According  to  Bergman, 
itU  found  in  the  fea  in  greater  plenty  than  any  o- 
ther  fait  except  the  fea-falt. 

1.  It  has  a  very  bitter  tafte  :  and  being  always 
mixed  in  the  fea-water,  it  is  the  principal  caufe 
o  its  bitternefs. 

2.  It  is  very  delifquefcent,  and  Tollable  in  a  fmall 
quantity  of  water. 

3.  All  the  alkalies,  even  the  cauftic  volatile  al 
kali  and  lime,  decompofe  it  by  precipitating  its 
bafis. 

4.  The  vitriolic,  nitrous,  and  boracic  acids  expel 
the  muriatic  acid  from  the  bafe  of  this  neutral 
fait. 

5.  Its  folution  does  not  trouble  that  of  nitrous  or 
marine  felenite  ;  but, 

6.  It  caufes  a  cloud  in  the  nitrous  folution  of  ul- 
ver. 

7.  The  vitriolic  acid  throws  down  no  vifible  pre 
cipitate  from  the  folution  of  this  neutral  fait. 

8.  Itlofes  its  acid  in  a  red  heat. 
XI.  Aerated  magnefia. 

Common  magnefia,  with  an  excefs  of  aerial  acid  is 

a  true  neutral  fair,  like  the  aerated  felenite  of 

p.  96,  col.  i.  and  becomes  foluble  in  cold  water. 

N  2  Othetwife 


C    136    ] 

Otberwife  it  is  fcarce  foluble  at  all ;  and  is  then 
cl  ailed  among  the  earths. 

This  neutral  fait  is  decompofable  by  fire,  by  which 
its  water  and  its  acid  are  expelled  j  and  it  may  be 
come  phofphoric. 

When  urged  by  fire,  it  agglutinates  a  little  :  and  fome 
pretended  that  it  melts.  But  it  mud  be  in  an  im 
pure  ftate  to  vitrify  at  all. 

The  three  mineral  acids,  and  the  alkalies,  dliTolve 
this  fait  with  efFervefcence,  by  expelling  the  ae 
rial  acid, 

XII,  Argillaceous  earth  combined  with  vitriolic  acid. 
The  alum  kind.  See  ALUM,  and  CHEMISTRY- 
ffte/fxt 

«.  With  a  ftnall  quantity  of  clay  j  native  or  plumofe 
alum, 

It  is  found  en  decayed  alum  ores  in  very  ftr.aH 
quantities ;  and  therefore,  through  ignorance, 
the  alabaftrkes  and  felenites,  both  of  which  are 
found  among  mod  of  the  alum  flates,  are  often 
rubilrtuted  in  its  Mead,  as  is  alib  fometimes  the 
afbeftus,  not  with  (binding  the  great  difference 
there  is  between  the  alum  and  thefe  both  in  rur 
gard  to  their  ufes  and  effects. 

I.  With  a  greater  quantity  of  pure  clay ;  white  alum 
ore. 

i.  Indurated  pale-red  alum  ore,  (fcltjius  alumtn'u 
Romanus.)  It  is  employed  at  Lumini,  not  far 
i^om  Civita  Vecchia  in  Italy,  to  make  the  pale- 
red  allum  called  rocb  allum.  This  is,  of  ail 
alum  ores,  the  moft  free  from  iron  ;  and  the 
reddifn  earth  which  can  be  precipitated  from 
it,  does  not  fnow  the  leaft  marks  of  any  metal 
lic  fubflance. 

r,  With  a  very  large  quantity  of  martial  clay,  which 
likewife  contains  an  inflammable  fubflance  ; 
Common  alum-  ore.     This  is  commonly  in 
durated 


C    13?    ] 

durated  and  ilaty,  and  is  therefore  general 
ly  called  alumjlate. 
It  is  found, 

i .  With  parallel  plates,  having  a  dull  furface  ; 
from  Andrarum  in  the  province  of  Skone, 
Hunneberg  and  Biilmgen  in  the  province  of 
Weft  erg  Gitl  and,  Rodoen  in  the  province  cf 
Jemtland,  and  the  ifland  of  Oeland,  &c.  In 
England,  the  great  alum  works  at  Whitby  in 
Yorkshire  are  of  this  kind. 

2.  Undulated  and  wedge-like,  with  a  Chining 
furiace.  This  at  the  firft  fight  refembles  pit- 
coal  ;  it  is  found  in  great  abundance  in  the  pa- 
rilh  of  Nas  in  Jemtland. 

XIII.  Argillaceous  earth  faturated  with  muriatic  acid. 
Argilia  falita. 

ProfelTor  Bergman  fays,  that  the  combinations 
of  the  argillaceous  earth  with  the  nitrous,  muria 
tic,  and  aerial  acids,  had  not  yet  been  found  na 
turally  formed  as  far  as  he  knew.  But  Dr  "Wi 
thering  affirms,  that  he  found  the  muriatic  argil 
to  exilt  in  a  considerable:  quantity,  in  the  Nevil 
Holt  water,  when  he  analyfed  that  mineral  water 
about  the  year  1777:  and  he  adds,  that  it  is  pro 
bably  contained  alfo  in  the  Bally caftle  water  i-ii 
Ireland. 

XIV.  Argillaceous  earth  mixed  with  volatile  alkali. 
[Although  this  mixture  is  by  no  means  a  neutral 

fait,  this  feems  to  be  the  place  to  treat  of  it  ac 
cording  to  the  order  of  faline  fubftances  adopted 
in  this  article.  1 

The  greateil  part  of  the  clays  contain  a  volatile  al 
kali,  which  difcovers  itfelf  in  the  diftillation  of  the 
fpirit  of  foa-falt,  &c. 


3  N  Or.isr 


C    138 


-£)rdkr  V.     METALLIC  SALTS. 

THE  native  falts  belonging  to  this  divifion  may  be 
djilinguiilied  by  the  pblogillicated  alkali,  which  preci 
pitates  them  ail.  The  few  which  have  faiine  proper 
ties,  according  to  the  definition  of  falts  formerly  gi 
ven,  fhall  be  mentioned  here  ;  referring  the  reft  to  the 
minei  allied  metals  ;  as  the  luna  eorneay  the  faiine  quick- 
Silver  or  murutic  mercury,  &c. 

I.  Vitriol  of  copper  ;  blue  vitriol.      Fitrioluw  veneris, 

f?u  cyprium. 

This  neutral  metallic  fait  is  a  combination  of 
the  vitriolic  acid  with  copper,  and  is  found  in  all 
ximent  waters,  as  they  are  called.  Its  colour  is  a 
deep  blue  ;  and  being  long  expofed  to  the  air,  it 
degenerates  into  a  nifty  yellow  blue.  Urged  by 
the  flame  of  the  blow-pipe  on  a  piece  of  charcoal, 
it  froths  at  firft  with  noife,  giving  a  green  flame, 
and  the  metallic  particles  are  often  reduced  to  a 
finning  globule  of  copper,  leaving  an  irregularly 
figured  icoria.  But  with  borax  the  fcoria  is 
diifolved,  and  forms  a  green  glafs. 

This  fait  rarely  occurs  cryftallifed  :  but  is  often 
found  naturally  diilblved  in  water  in  Hungary, 
Sweden,  and  Ireland  :  from  this  water  a  blue  vi 
triol  is  generally  prepared,  Thefe  natural  wa 
ters  are  called  cemen:atory  or  cementing  ones.  Ac 
cording  to  Monet,  this  concrete  fait,  when  found 
naturally  formed,  only  proceeds  from  the  evapo 
ration  of  fitch  waters.  It  is  alfo  occafionaliy  ex 
tracted  from  fulphurated  copper  ores  after  torre- 
faction.  See  CHEMISTRY-/^/*?.*,  at  vitriol. 

II.  Muriatic  copper,  or  marine  fait  of  copper.    Cuprum 
fallium. 

This  fait  has  been  found  in  Saxony,  in  the  mine 


of  Johngeorgenftadt.       I.    It    is    of  a  greenifh 
colour,  and  foliated  te 


xture.     2.   It  is  moderate- 


[     139    1 

ly  hard.     3.  Sometimes  it  is  transparent  and  cry- 
ftallifed. 

It  has  been  taken  for  a  kind  of  mica :  but  Pro- 
feiibr  Bergman  found  it  to  confift  of  copper 
and  marine  acid,  with  a  little  argillaceous  earth. 

Another  fpecimen  of  a  purer  fort  was  depofited 
in  the  mufeum  of  Upfal.  This  is  of  a  bluifh 
green  colour,  and  friable.  It  effervefced  with  ni 
trous  acid,  to  which  it  gave  a  green  colour :  and 
by  adding  a  proper  folution  of  filver,  a  luna  cor 
nea  was  formed,  by  which  the  prefence  of  the 
muriatic  acid  was  afcertained.  ( Kirivan  and  Berg 
man.  ) 

III.  Martial  vitriol ;  vitriol  of  iron.     Common  green 
vitriol  or  copperas. 

This  is  the  common  green  vitriol,  which  is  na 
turally  found  diifolved  in  water,  and  is  produced 
in  abundance  by  decayed  or  calcined  marcaiites. 

This  metallic  neutral  fait  refults  from  the  com 
bination  of  the  vitriolic  acid  with  iron. 

1.  It  is  of  a  greenifh  colour  when  perfectly  and 
recently  cryftallifed  ;  but, 

2.  Efflorcfces  by  being  expofed  to  the  air,  be 
comes  yellowifh,  and  is  covered  with  a  kind  of 
ruft.      Sometimes  it  becomes  white  by  long 
{landing. 

3.  It  requires  fix  times  its  weight  of  water,  in 
the  temperature  of  60  degrees,  to  be  diilblved. 

4.  It  has  an  aftringent,  harfh,  and  acidulous  tafte. 

5.  Expofed  to  a  moderate  heat,  even  to  that  cf 
the  funiuine,  it  falls  into  a  yellowiih  powder  : 
but, 

6.  On  being  expofed  to  a  fudden  heat,  it  melts  ; 
and  on  cooling,  aflumes  a  whitiih  brown  colour. 

7.  When  ftrongly  urged  by  fire,  it  lofes  its  acid, 
becomes  of  a  dark  red  colour,  and  is  then  call 
ed  colcothar  ;  a  powder  which  is  employed  in 
polutung  metals,  and  to  which  the  artifts  have 

applied 


C     HO     3 

applied  the  improper  name  of  crocus  martis, 
though  this  name  only  belongs  to  the  yellow 
preparations  of  the  iron-calces,  ufed  in  phar 
macy  and  in  enamelling,  &c. 

8.  Pure  fixed  alkali  precipitates  the  iron  from  its 
folution  in  deep  green  flakes ;  the  mild  alkali, 
in  a  greenifh  white  colour  ;  pure  volatile  alka 
li,  in  fo  deep  a  green,  that  it  appears   black ; 
but  the  mild  volatile  alkali  precipitates  it  in  a 
greyifh-green  colour. 

9.  All  vegetable  aftringents,  as  the  tindure  of  tea, 
quinquina,  gales,  &c.  precipitate  the  iron  in  a 
black  colour:    hence    they   are   ufed   as  teds 
to  difcover  its  pretence  in  chemical  analyfes  ; 
and  it  is  from  this  black  precipitate   that  the 
common  writing  ink  is  made,  being  diluted 
in  water,  and  there  fufpended  by  the  Arabic  or 
Senegal  gums. 

10.  One  hundred  parts  of  this  fait,  recently  cry- 
ftallifed,  contain  20  of  real  vitriolic  acid,  25  of 
iron,  and  55  of  water. 

11.  Its   acid   is   known  by  this,    that  its   folu 
tion  mixes  without  turbidity  with  the  folutions 
of  other  falts  that  contain  vitriolic  acid  ;  ;:s 
Epfom,  felenite,  vitriolated  tartar,  &c. 

12.  And  the  bafis  of  this  metallic  fait  is  known 
by  the  black  colour  produced  by  the  folution 
of  vegetable  aftringents. 

13.  On  being  urged  by  the  fiame  thrown  by  the 
blow-pipe,  it  offers  the  fame  phenomena  as  the 
vitriol  of  copper,  except  that  it  does  not  colour 
the  flame. 

Green  vitriol  is  frequently  found  native,  ei 
ther  in  coal  mines  or  in  the  cavities  of  pyriui- 
ceous  mines,  or  adhering  to  their  fcaffolds  in  a 
ftalaclitical  form.  It  is  found  alfo  in  fmall 
round  ftones,  called  ink-Jlonef,  of  a  white,  red, 
grey,  yellow,  or  black  colour,  which  ar,e  almoft 

iblubie 


foluble  in  water,  and  contain  a  portion  of  copper 
and  zinc.  Alfo  fometimes  in  form  of  fchiftus 
or  flaty  pyritaceous  ftones.  But  the  greateft 
part  of  that  in  ufe  is  prepared  by  art,  from  the 
martial  pyrites  or  mundic.  See  CHEMISTRY, 
n°  619. 
IV.  Aerated  iron.  Ferrum  aeratum. 

This  metallic  fait  is  a  combination  of  the  ae 
rial  acid  with  iron ;  and  is  found  in  the  light 
chalybeate  waters,  where  it  is  diffolved  by  an  ex- 
cefs  of  this  acid. 

Mr  Lane  was  the  firft  who  discovered  in  Eng 
land  the  aclion  of  the  aerial  acid  on  iron,  when, 
the  water  is  impregnated  with  that  menftruum. 
The  late  R.  Rouelle  demonftrated  the  fame 
phenomenon  in  France  upon  this  and  other  me 
tals.  But  ProferTor  Bergman  Teems  to  have  pre 
ceded  them  both  nearly  about  the  fame  time, 
though  neither  had  any  knowledge  of  each  other's 
difcoveries. 

The  great  volatility  of  this  acid  i-s  the  caufe  why 
this  neutral  fait  is  not  often  found.  For  the 
mere  evaporation  of  the  ferruginous  mineral  wa 
ters,  in  order  to  analyfe  them,  is  fufficient  to  let 
loofe  the  aerial  acid  ;  To  that  the  iron  which  was 
there  diffolved  by  its  power  falls  down  to  the 
bottom  in  the  from  of  a  light  ore,  which  amounts 
to  nearly  TT  *TT  of  the  weight  of  the  water  ;  and 
when  frefh  retains  fo  much  phlogifton  as  to  obey 
the  magnet,  as  Bergman  Says. 
V.  Vitriol  of  cobalt,  or  vitriolated  cobalt. 

This  metallic  fait  refults  from  the  combination  of 
the  vitriolic  acid  with  cobalt. 
i.  When  found  native,  it  is  always  in  an  efHo- 
refcent   ftate  ;  whence    it  arifes  that,  in  this 
cafe, 

?.  Its  colour  is  greenifh,  mixed  with  a  grey  tint : 
but, 


C    >4*    1 

3.  It  is  of  a  rofy  colour  when  artificially  made  ; 

4.  Efflorefces  when  expofed  to  the  action  of  the 
atmofphere  ;  and, 

5.  Takes  then  a  greenifh  colour  mixed  with  a 
pale  purple,  or  a  LiTias  colour,  as  the  French 
call  it. 

6.  It  is  difficultly  foluble  in  water ;  and, 

7.  Its  folution  is  of  a  red  colour. 

8.  The  phlogifticated  alkali  precipitates  the  co 
balt  from  the  folution  of  this  fait,  which  with 
borax  gives  an  azure  glafs. 

By  the  above  qualities,  chiefly  the  rofy  co 
lour  of  the  folution  of  this  neutral  fait,  its  ba- 
fis  is  fufficiently  diftinguifhed.  As  to  its  acid, 
it  is  eafily  known  by  the  fame  tefts  as  thofe  of 
the  preceding  vitriols. 

It   is   laid  to  be  found  native  in  fmall  pieces, 
mixed  with  a  greenifh  efflorefcence  in  cobalt 
mines.      (Kirwan  and  Mongez.) 
VI.  Vitriol  of  zinc,  vkriolated  zinc,  or  white  vitriol. 
This  neutral  metallic  fait  refuks  from  the  combina 
tion  of  vitriolic  acid  with  zinc. 
j.  Its  colour  is  white.     It, 

2.  Requires  little  more  than  twice  its  weight  cf 
water  to  dilTolve  it  in  the  temperature  of  60 
degrees  of  Fahrenheit's  thermometer^  and  de- 
pofits  a  greyiih  yellow  powder. 

3.  Its  fpecific  gravity  is  2000. 

4.  Its  tafte  is  very  ftyptic. 

5.  It  mixes  uniformly  with  vitriolic  neutral  falts. 
j6.  Precipitates  nitrous  or  marine  felenites  from 

their  folutions,  by  which  its  acid  is  afcer- 
tained. 

7.  It  is  precipitable  in  a  whitifh  powder  by  al 
kalies  and  earths ;  but, 

8.  Neither  ii  en,  copper,  nor  zinc,  precipitate  it : 
by  which  circumftance  its  bafis  is  fufficiently 
indicated. 

9.  if 


[     143     ] 

9.  If  it  contains  any  other  metallic  principle, 
this  may  be  precipitated  by  adding  more  zinc 
to  the  folution  ;  excepting  iron,  which  will 
of  itfelf  precipitate  by  expofure  to  the  air  or 
boiling  in  an  open  velTel. 

10.  One  hundred  parts  of  this  metallic  fait  con 
tain  22  of  vitriolic  acid,  20  of  zinc,  and  58 
of  water. 

1 1 .  Urged  by  fire,  it  lofes  a  good  part  of  its  acid. 

12.  Treated  with  the  blow-pipe  it  exhibits  nearly 
the  fame  phenomena  as  other  metallic  vitri 
ols  ;  except  only  that  the  flame  is  brilliant 

.  when  the  zinc  is  reduced,  and  gives  out  white 
floes  called  Jlowers  of  zinc. 

This  neutral  metallic  fait  is  fometimes  found 
v  native,  mixed  with  vitriol  of  iron,  and  in  the 
form  of  white  hairy  cryftals  ;  or  in  a  ilalac- 
titical  form  in  the  mines  of  Hungary, .  cr 
as  an  efflorefcence  on  ores  of  zinc.  It  is  alfo 
found  difiblved  in  mineral  waters,  and  gene 
rally  with  feme  proportion  of  vitriols  of  iron 
and  copper.  Bergman  fays  it  is  fometimes 
produced  by  the  decompofition  of  pfeudoga- 
Issna,  or  black-jack  ;  but  this  rarely  happens, 
becaufe  this  iubftance  does  not  readily  decom- 
pofe  fpontaneoufly. 

But  that  in  common  life  is  moftly  prepared 
at  Gofiaar,  from  an  ore  "which  contains  zinc, 
copper,  and  lead,  mineralifed  by  fulphur  and 
a  little  iron.  The  copper  is  firft  feparated  as 
much  as  poffible  :  the  remainder  after  torre- 
faction  and  diftillation  is  thrown  red-hot  into 
water  and  lixiviated.  It  is  never  free  from 
iron.  (  Kirwan,  Mongez. ) 
VII.  Variolated  nickel,  or  vitriol  of  nickel. 

This  neutral  metallic  fait  refults  from  the  com 
bination  of  the  vitriolic  acid  with  nickel.  It  ex- 
ills  fometimes  in  confequence  of  the  decornpofi- 

tion 


C    144   3 

tion  of  the  fulphureous  ores  of  this  femimetal. 
It  is  found  native,  effiorefcing  on  Kupfer-nickel ; 
and  generally  mixed  with  vitriol  of  iron. — It  is 
of  a  green  Colour,  as  well  as  its  foliation.  It  is 
precipitated  by  zinc  ;  but  when  joined  with  iron, 
this  laft  is  not  precipitated  by  the  fame. 

Its  origin  is  perhaps  owi::g  to  the  decompofition 
of  the  pyritaceous  and  fulphureous  ore  of  Kupfer- 
nickel,  mentioned  by  Waller  ins.  This  ore  con 
tains  a  great  quantity  of  arfenic  and  fulphur,  as 
well  as  cobalt,  nickel,  and  iron.  And  if  it  comes 
to  be  decompofed  in  the  b  .wcls  of  the  earth,  it 
is  natural  to  expect  that  'he  vitriolic  acid  of  the 
fulphur  will  atu  ckel  and  the  iron,  with 

which  it  will  form  neutral  metallic  falts  (Mongez, 
Kir  wan. ) 
VIII.  Muriatic  mangane.         Manganejitim  falitnm. 

M.  Hielm  is  the  only  perfon  who  has  as  yet 
found  this  middle  fait  in  fome  mineral  waters  of 
Sweden.  It  is  ccmpofed  by  the  combination  of 
the  regulus  of  Mauganefe  with  muriatic  acid. 

i.  It  is  precipitated  of  a  whitlih  yellow  colour, 
by  the  Pruffian  (phlogiflicated)  alkali;  and  of  a 
brownifh  yellow,  by  the  mineral  alkali.  2.  It 
does  not  cryftallife  in  any  diftinct  form.  3.  It 
abftracls  the  moifture  of  the  air.  4.  To  obtain 
its  bafis  free  from  iron,  it  muft  be  precipitated 
by  the  mineral  alkali ;  rediilblved  in  nitrous  acid  ; 
then  calcined  until  this  acid  is  expelled ;  and  the 
refiduum  is  to  be  treated  with  difliiled  vinegar, 
which  will  then  take  up  only  the  manganefe. 
(  Ktriuan. ) 

Order.  VI.     TRIPLE   SALTS. 

THE  neutral  falts  hitherto  enumerated  are  fitch  as 

•arc  compofed  of  two  ingredients  only  ;  but  fometimes 

three  or  more  are  fo  united  as  not  to  be  feparated  by 

i  cryftalli- 


[     '45     3 

cryftallization.  The  vitriols  that  we  are  acquainted 
with  are  hardly  ever  pure ;  and  two  or  three  of  them 
fometimes  are  joined  together. 

Sometimes  likewife  it  happens  that  neutral  falts  join 
earthy  falts,  and  earthy  falts  metallic  ones,  Bergman 
generally  diftinguiihes  compound  falts  according  to 
the  number  of  their  principles,  whether  the  fame  acid 
be  joined  to  feveral  bafes,  or  the  fame  bafe  to  diffe 
rent  acids  ;  or,  laftly,  whether  feveral  menftrua  and 
feveral  bafes  are  joined  together.  Hence  arife  falts 
triple,  quadruple,  &c.  which  the  diligence  of  after- 
times  muft  illuftrate.  The  mod  remarkable  examples 
of  triple  and  quadruple  native  falts  which  have  yet 
occurred  are, 
I.  Mineral  alkali,  with  a  fmall  quantity  of  calcareous 

earth.     Alkali  falls  communis.      Aphronitrum. 
This    is  fo    ftrongly  united    with    the    calcareous 
earth,  that  the  latter  enters  with  it  into  the  very 
cryftals  of  the  fait :  though  by  repeated  folutions 
the  earth  is  by  degrees  feparated  from  it,  and 
falls  to  the  bottom  after  every  folution. 
It  grows  in  form  of   white   froft   on  walls,    and 
under  vaults  ;  and  in  places  where  it  cannot  be 
wafhed  away  by  the  rain. 

Hence  it  would  appear,  that  this  is  not  only  a 
triple,  but  a  multiple  fait ;  as  thefe  pieces  of  old 
mortar  covered  with  this  white  froft,  on  ancient 
walls,  are  the  very  fame  from  which  the  faltpetre 
makers  extract  the  mother- water  of  nitre,  after 
mixing  therewith  the  vegetable  afhes,  to  furnifli 
the  alkaline  bafe  to  it.  M.  Fourcroy  fays  in  his 
feventeenth  Lefture,  that  this  mother-water  con 
tains  not  only  nitre,  but  five  other  kinds  of  fait, 
viz.  the  marine  fait,  nitrous  magne/ia,  calcareous 
nitre,  magnsfta  nitrata,  and  calx  Jalita  ;  to  which 
the  chemifts  of  Dijon  add  the  digeft'mt  fait  of  Syl 
vius,  and  in  fome  cafes  various  vitriols  with  alka 
line  or  earthy  bafes. 

O  When 


C" 

s  When    it    contains    any    confidera'ble    quantity  of 

.       the  calcareous  earth,  its  chryftals  become  rhom- 

boidal,  a  figure  which  the  calcareous  earth  often 

affumes  in  inooting  into  chryftals :  but  when  it  is 

purer,  the  cryftals  Ihoot  into  a  prifmatic  figure. 

,  This  is  a  circumftance  which  neceiFarily  muft  con- 

jfufe    thofe  who    know    the  falts    only  by  their 

figure, ;  and  ihows,  at  the  fame  time,  how  little 

certainty  fuch  external  marks   afford  in   a  true 

diftincHon  of  things. 

This  fait  is  very   often  confounded  with  the 
fal  mirabile  Glauber  i. 

II.  Common  fait  with  magnefia  ;  or  muriatic  mineral 

alkali  contaminated  by  muriatic  magnefia. 
;  This  is  a  compound  of  the  common  fait  with 
muriatic  magnefia  :  and  by  the  expreilion  conta 
minated  (inqulnatum)  of  profelfor  Bergman',  we 
may  fuppofe  that  the  magnefian  fait  is  not  inti 
mately  united  to  the  alkaline  b^rfe. 
Tliis  triple  fait  is  very  deliquefcent ;  a  quality 
it  owes  to  its  integrant  part,  the  muriatic  magne- 
ila,  (p.  79.  co.l.  i.)  For  the  pure  muriatic  alkali 
does  not  deliquefce :  but  this  degree  of  purity  is 
feldom  found,  even  in  the  native  foffil  offal  gem, 
(p.  93.  col.  2.)  In  general  all  the  earthy  marine 
falts  are  very  deliquefcent-,  as  the  muriatic  chalk, 
the  muriatic  barytes,  and  the  muriatic  magnefia. 
Bergman,  Macquer^  and  Jhlongez. 

III.  Mineral  alkali  with  fuccinous  acid  and  phlogifton. 
This  fub (lance  will  be  afterwards  mentioned  among 

the  inflammables. 

IV.  Vitriolated  magnefia  with  vitriol  of  iron.  Epfom 
fait  contaminated  with  copperas. 

.  •  Found  in  fome  mineral  waters,  according  to  Mr  Mo 
net,  (Treattfe  on  Mineral  Waters.) 

V.  Native-alum  contaminated  by  copperas.     Vitriola 


ted  argil  with  vitriol  of  iron. 


Found 


C     H7     1 

Found   in    the  aluminous    fchiPcus.     It  fometimes 
effiorefces   in  a  feathery  form.     Perhaps  this  is 
the  plumofs  alum  of  the  ancients. 
VI'.  Native  alum,  contaminated  by  fulphur. 

At  the  places  about  Wednefbury  and  Bilflon,  in 
Staffordshire,  where  the  coal-pits  are  on  firej 
this  fubftance  fublimes  to  the  furface  ;  and  may 
be  collected,  in  confiderable  quantity,  during  dry 
or  frofty  weatlier. 

A  fmiilar  compound  fubftance  fublimss  at  the 
Solfaterra  near  Naples. 

VII.  Native  alum  contaminated  by  vitriolated  cobalt. 
In  the  mines  of  Herregrund  and  Idria  this  fait 

may  be  feen  (hooting  out  into  long  {lender  fi> 
laments.  Perhaps  this  is  the  tnchi'es  of  the 
Greeks. 

1.  DiiTolved  in  water,  it  immediately  betrays 
the  prefence  of  vitriolic  acid   upon  the  ad 
dition  of  terra  ponderofa  falita  (muriatic"  acid 
faturated  with  heavy  earth). 

2.  By  the  addition  of  phlogiflicated  alkali,  a 
precipitate  of  cobalt  is  thrown  down,  which 
makes  blue  glafs  with  borax  or  microcofmic 
ialt.     (B:rg.  Sci^.} 

VIII.  Vitriol  of  copper  with  iron. 

This  fait  is  of  a  bluifh-green  colour.  It  is  the 
wirio/urn  ferreo-ctipreum  cyamum  of  LinnGeus.  Its 
colour  varies,  being  fometimes  more  orlefs  greeny* 
and  fometimes  more  or  lefs  blue.  It  is  found  at 
Saluberg  and  at  Falhun.  This  vitriol  is  called 
vit/iol  of  Hungary  becaufe  it  is  found  ia  the 
Hungarian  mines  of  this  kind.  (Monger.) 

IX.  Vitriol  of  copper,  iron,  and  zinc. 

This  is  the  •oittiolum  ferreo  zincs?)  cupreu-r.  cyin?i'.~T. 
of  Linnxus.  Its  colour  is  of  a  blue  incliiv- 
ing  to  green.  If  rubbed  on  a  polifhed  furface  of 
iron,  the  copper  is  not  precipitated  thereby,  as 
it  happens  to  the  blue  vitriol;,  which  (hows  th?.- 
O  2  thi 


the  vitriolic  acid  is  perfeclly  faturated  in  this  fait 
by  the  three  metallic  bafes. 

X.  Vitriol  of  copper  and  zinc. 

This  is  the  blue  vitriol  from  Collar,  According 
to  Mongez  it  is  the  vitrwlum  mnceo-cufreuin  cacru* 
kum  of  Linnaeus. 

XI.  Vitriol  of  iron  and  zinc. 

This    is    the    green    vitriol    from    Collar    in    the 
Hartz.     According  to  Monger,  this  in  the  vitri- 
v/um  %inc£Q-firreum  i)ir'ide  of  Linnaeus,  105*  6.     Its 
colour  is  a  pale-green  caft. 
XI L  Vitriol  of  iron  and  nickel. 

This  fait  is  of  a  deep-green  colour,  and  is  con 
tained  in  the  ochre,  or  decayed  parts  of  the  nic 
kel,  at  the  cobalt-mines  of  Los,  in  the  province 
of  Helfmgland. 


CLASS  III.  MINERAL  INFLAMMABLE  SUB- 

STANCES. 

To  this  clafs  belong  all  thofe  fubterraneous  bodies 
that  are  diffoluble  in  oils,  but  not  in  water,  which  they 
repel ;  that  catch  flame  in  the  fire  ;  and  that  are  elec 
trical. 

It  is  difficult  to  determine  what  conftitutes  the  dif 
ference  between  the  purer  forts  of  this  clafs,  fince  they 
all  muft  be  tried  by  fire,  in  which  they  all  yield  the 
fame  product ;  but  thofe  which  in  the  fire  (how  their 
differences  by  containing  different  fubftances,  are  here 
<:onfidered  as  being  mixed  with  heterogeneous  bodies : 
that  fmall  quantity  of  earthy  fubftance,  -which  allphlo- 
gifta  leave  behind  in  the  fire,  is,  however,  not  attend 
ed  to. 
I.  Inflammable  air ;  fire  damp. 

This  aeriform  fubftance  is  eafily  known  by  its 
property  of  inflaming  when  mixed  with  twice  or 
thrice  its  bulk  of  common  atmofpheric  air;  and 

it 


L    149    J 

il  is  afierted  to  be  the  real  phlogiftonalmoft  pure, 
See  AEROLOGY-//?^/?.*  and  INFLAMMABLE  Air. 

It  admits  coniiderable  varieties,  according  to  the 
nature  cf  the  fubitances  from  which  it  is  pro- 
oinced,  and  often  gives  different  refiduums  upon 
combuftion,  fome  of  which  are  of  the  acid  kind. 
If  it  is  produced  from  charcoal,  it  yields  aerial 
acid  or  fixed  air :  from  folutions  of  metallic  fub- 
ftances  in  the  vitriolic,  nitrous,  or  marine  acids, 
it  yields  thefe  refpeclive  acids,  as  M.  Lavoifrer 
admits. 

./Edier,  converted  into  vapour  in  a  vacuum,  gives 
a  permanent  elaflic  vapour,  which  is  inflam 
mable.  The  atrnofphere,  which  floats  round  the 
fraxinella,  is  inflammable  from  the  admixture, 
of  its  vapours,  which  feem  to  be  of  the  nature  of 
an  effential  oil  :  fo  that  on  approaching  the  flame 
of  a  candle  under  this  plant,  in  hot  weather,  it 
takes  fire  in  an  inftant;  although  the  effential  oil, 
extracted  from  this  plant  by  diftillation,  is  not  in 
flammable  on  account  of  the  watery  particles 
mixed  with  it,  as  M.  Bomare  aiferts. 

Mr  Scheele  is  of  opinion,  that  every  inflamma 
ble  air  is  ccmpofed  of  a  very  fubtile  oil.  This 
coincides  with  the  idea  entertained  by  chemiftsoF 
their  phlogiiion;  and  is  confirmed  by  the  facly 
cf  its  being  naturally  foufitl  in  thofefprings  from 
whence  iifues  petrol,  whole  exhalations  are  very 
inflammable. 

The  refiduum,  which  remains  in  the  atmofphers 
after  the  combuilion  of  inflammable  air,  is  ex-, 
trcmely  noxious  to  animals.  Doftor  Prieftley 
takes  it  to  be  a  combination  of  phlogifton  v  ith 
fiure  air,  and  on  this  account  calls  it  phlo^tfti- 
caled  air.  But  M.  Lavoifier,  on  the  contrary, 
eonfiders  it  to  be  a  primitive  fubfta.'ics  of  an  un- 
•  changeable  nature,  and  give:-  it  ,the  finguhur  n.'.mc 
«f  atmvf&heric  mephil'.s. 

O  3  IL.  He- 


C     '5°     ] 

II.  Hepatic  air. 

This  air  feems  to  confift  of  fulphur,  held  in  fo- 
lulion  in  vitriolic  or  marine  air.  It  is  inflam 
mable  when  mixed  with  three  quarters  of  its 
bulk  of  common  air.  Nitre  will  take  up  about 
half  the  bulk  of  this  air  ;  and  when  faturated 
with  it,  will  turn  filver  black  :  but  if  ftrong  de- 
phlogifticated  nitrous  acid  be  dropped  into  this 
water,  the  fulphur  will  be  precipitated. 

One  hundred  cubic  inches  of  this  air  may  hold 
eight  grains  of  fulphur  in  folution  in  the  tempe 
rature  of  60°;  and  more  if  hotter. 

Atmofpheric  air  alfo  decompofes  hepatic  air. 

It  is  found  in  many  mineral  waters,  and  particu 
larly  in  the  hot  baths  of  Aix-la-Chapelle.  The 
caufe  and  mannerof  their  containing  fulphur  which 
was  long  a  problem,  has  at  laft  been  happily  ex 
plained  by  Mr  Bergman. 

It  plentifully  occurs  in  the  neighbourhood  of  vol 
canoes  and  in  feveral  mines. 

Hepatic  air  is  eafily  obtained  by  art,  from  all 
forts  of  liver  of  fulphur,  whether  the  bafe  be  an 
alkali,  an  earth,  or  a  metal,  if  any  acid  is  poured 
upon  it  ;  and  the  better,  if  ufe  be  made  of  the 
marine  acid,  becaufeitcontains  phlogifton  enough, 
and  does  not  fo  ilrongly  attra<5l  that  of  the  hepar 
fulphuris.  For  this  reafon  the  nitrous  acid  is  not 
fit  for  this  procefs,  as  it  combines  itfelf  with  the 
phlogifton,  and  produces  nitrous  air.  It  may 
iilfo  be  produced,  by  diftilling  a  mixture  of  ful 
phur  and  powdered  charcoal,  or  of  fulphur  and 
oil,  &c.  See  the  detached  article  HEPATIC  Air, 
and  AEROLOGY-///^  -x. 

III.  Phlogifton  combined    with  aerial  acid;    black 
lead,  or  wadd,     Plumlago,  See  the  detached  article 


It  is  found, 

a.  Of 


[  'Jl  ] 

*.  Of  a  fteel-graincd  and  dull  texture.  It  is  na 
turally  black,  but  when  rubbed  it  gives  a  dark 
lead  colour. 

b.  Of  a  fine  fcaly,  and  coarfe-graincd  texture ; 
coarfe  black-lead. 

IV.  Mineral  tallow.     Serum  minerale. 

This  was  found  in  the  lea  on  the  coafts  of  Fin 
land  in  the  year  1736.  Its  fpecific  gravity 
is  0.770;  whereas  that  of  tallow  is  0.969.  It 
burns  with  a  blue  flame,  and  a  fmell  of  greafe, 
leaving  a  black  vifcid  matter,  which  is  with  more 
difficulty  confumed. 

It  is  foluble  in  fpirit  of  wine  only  when  tarta- 
rifed:  and  even  then  leaves  an  infoluble  reii- 
duum ;  but  exprefled  oils  diflblve  it  when  boil 
ing. 

It  is  alfo  found  in  fome  rocky  parts  of  Perfia, 
but  feems  mixed  with  petrol,  and  is  there  called 
fchebennaadj  tfienpin^  kodrett. 

Dr  Herman  of  Strafburg  mentions  a  fpring  in  the 
neighbourhood  of  that  city,  which  contains  a 
fubftance  of  this  fort  difFufed  through  it,  which 
feparates  on  ebullition,  and  may  then  be  col 
lected.  (Kiriuan). 

V.  Ambergris.     Ambra  grlfea. 

It  is  commonly  fuppofed  to  belong  to  the  mi 
neral  kingdem,  although  it  is  faid  to  have  doubt 
ful  marks  of  its  origin  (A). 

a  It 


(A)  Ambergris,  according  to  the  aflertion  of  M. 
Aublet  in  his  Hijloire  de  la  Guiane},  is  nothing  more 
than  the  juice  cf  a  tree  infpiflated  by  evaporation  in 
to  a  concrete  form.  This  tree  grows  in  Guyana, 
and  is  called  cuma  but  has  not  been  inveftigated  by- 
other  botanifts.  When  fome  branches  are  broken  by 
high  winds,  a  large  quantity  of  the  juice  comes  out ; 


#.  It  has  an  agreeable  fmell,  chiefly  \vhen  burnt : 

b.  Is  confumed  in  an  open  fire  : 

c.  Softens   in  a  flight  degree  of  warmth,  fo  as 
to  (tick  to  the  teeth  like  pitch. 

d.  It 


and  if  it  chances  to  have  time  to  dry,  various  maiies 
(fome  of  which  had  been  fo  large  as  to  weigh  1200 
pounds  and  more)  are  carried  into  the  rivers  by  hea 
vy  rains,  and  through  them  into  the  fea  :  afterwards 
they  are  either  thrown  into  the  ihore  or  eaten  by 
fome  fifh,  chiefly  the  fpermaceti  whale,  known  by  the 
name  of  fibyfettr-macroftpbalus  among  ichthyologiils. 
This  kind  of  whale,  is  very  greedy  of  this  gum-refm, 
and  fwallows  fuch  large  quantities  when  they  meet 
with  it,  that  they  generally  become  fick  ;  fo  that  theie. 
employed  in  the  filliery  of  thefe  whales,- always  ex- 
peci  to  find  fome  amber  mixed  with  the  excrements 
and  remains  of  other  food  in  the  bowels  of  thofe 
whales  who  are  lean.  Various  authors,  :;mong  whom 
is  Father  Santos  in  his  Ethiopia  Orkntalis,  \\ho  travel- 
1-ed  to  various  places  of  the  African  coaft,  and  Bomare, 
fay,  that  fome  fpecies  of  birds  are  fond  of  eating 
this  fubftance  as  well  as  the  whales  and  other  fifhes- 
This  accounts  very  well  for  the  claws,  beaks,  bones, 
and  feathers  of  birds,  parts  of  vegetables,  fhells,  and 
bones  of  fifh,  and  particularly  for  the  beaks  of  the 
cuttle  fifh  or  fepia  oftopedia,  that  are  fometimes  found 
in  the  mafs  of  this  fubftance.  Dr  Swediar,  however, 
attended  only  to  thefe  laft,  though  he  had  mentioned 
alfo  the  other  fubftances  in  his  paper  inferted  in  the 
Philofophical  Tranfaclions  for  1783  ;  wherein  he  at 
tempts  to  eftablifh  an  opinion,  that  the  amber  is  no 
thing  elfe  but  a  preternaturaliy  hardened  dung,  or 
feces,  of  the  phyfetcr'  whale.  Dr  Withering  and  Mr 
Kirwan  have  embraced  this  notion  ;  as  did  alfo,  inad 
vertently,  the  editors  of  this  Work.  See 'AMBER.-.' 

GRIS. 


C     «53     ] 

t!*  It  is  of  a  black  or  grey  colour ;  and  of  a  dull 

or  fine  grained  texture  (B). 

The  grey  is  reckoned  the  beft,  and  is  fold  very 
dear.  This  drug  is  brought  to  Europe  from  the 
Indies.  It  is  employed  in  medicine ;  and  alfo  as 
a  perfume  (c). 

VI. 


(B)  Mr  Aublet  brought  fpecimens  of  this  gum- 
refm,  which  he  collected  on  the  fpot,  from  the  cuma 
tree  at  Guiane.  It  is  of  a  whitifh-brown  colour  with 
a  yellowifh  (liade,  and  melts  and  burns  like  wax  on 
the  fire.  The  fingularity  of  this  gum-refm  is,  that  it 
imbibes  very  ftrongly  the  frnell  of  the  aromatic  Al 
liances  which  furround  it ;  and  it  is  well  known  that 
perfumers  avail  tbemfelves  very  confiderably  of  this 
advantage.  M.  Rouelle  examined  very  carefully  this 
fubdance  brought  over  by  Mr  Aublet,  and  found  that 
it  produced  the  very  fame  refults  as  in  other  good  kinds 
of  amber.  Befides  Mr  Aublet's  authority,  which  is 
decifive,  as  being  grounded  upon  direct  proofs  of  faft, 
Rumphius,  quoted  by  Bergman,  long  fince  menti 
oned  a  tree  called  Nanarlum,  whofe  infpiflated  juice 
refembles  amber.  It  cannot  therefore  at  prefent  be 
doubted  that  the  origin  of  this  phlogiftic  fubftance  is 
the  vegetable  kingdom,  although  it  may  be  often  found 
and  reputed  as  a  product  of  the  foffile  kind. 

This  fubftance  being  analyfed  by  Meflrs  Geoffrey 
and  Newman,  quoted  by  M.  Fourcroy,  yielded  them 
the  fame  principles  as  the  bitumens ;  viz.  anacidfpirit, 
a  concrete  acid  fait,  forne  oil,  and  a  charry  refiduum  : 
which  evidently  evinces,  that  all  thefe  fat  and  oily 
foffile  fubiiances  have  their  origin  from  the  other  tw<* 
kingdoms  of  nature. 

(c)  Ambergris  is  not  only  brought  from  the  Eaft 
Indies,  but  trom  the  coafts  of  the  Bahama  Iflands, 
Brafil,  Madagafcar,  Africa,  China,  Japan,  the  Moluc 
ca 


L     '54     3 

VI.  Amber.  Airibra  JJavat  fuccinnm,  eleftrum,  Lat. 
Carale,  French.  Agtjlem^  Bernjkln,  Germ. 

This  fubftance  is  dug  out  of  the  earth,  and  found 
on  the  fea-coafts.  According  to  the  experi 
ments  of  M.  Bourdelin,  it  confifts  of  an  in 
flammable  fubftance,  united  with  the  acid  of 

"  common  fait,  which  feems  to  have  given  it  its 
hardnefs. 

It  is  fuppofed  to  be   of  vegetable    origin,  fmce   it 

.  is  laid  to  be  found  together  with  wood  in  the 
earth. 

By  Diftillaticn  it  yields  water,  oil,  and  a  volatile 
acid  fait,  which  the  abovementioned  author  has 

thought 


ca  iflands,  the  coafts  of  Coromandel,  Sumatra,  &c.  Dr 
Lippert,  in  a  treatife  he  publifhed  at  Vienna  1782, 
entitled  Phlogiftchgia  Mineralis,  has  copied  chiefly 
from  Wallerius  what  he  aflerts  of  this  fubftance.  He 
affirms  that  there  are  eight  known  fpecies  of  amber; 
five  of  a  fingle  colour,  viz.  the  white  and  the  black 
from  the  ifland  of  Nicobar,  in  the  gulph  of  Bengal, 
the  alh-coloured,  the  yellow,  and  the  blackifh  ;  and 
two  variegated,  viz.  the  grey  coloured  with  black 
fpecks,  and  the  grey  with  yellow  fpecks.  This  lad 
he  afferts  to  be  the  moil  efteemed  on  account  of  its 
very  fragranc  fmell,  and  to  come  from  the  South 
coaft  of  Africa  and  Madagafcar,  as  v.-ell  as  from 
Sumatra;  and  that  the  black  dark  coloured  amber 
is  often  found  in  the  bowels  of  cetaceous  fifhes.  Thd 
fame  author  adds  alfo  from  Wallerius,  that  by  difttl- 
ling  the  oil  of  yellow  amber  (fucdnum)  with  three 
parts  and  a  half  of  fuming  "nitrous  acid,  a  refiduum 
remains  like  rofin,  which  emits,  a  perfect  fmell  of 
nuifk ;  whence  fome  conclude,  that  the  ambergris 
belongs  to  thevfolnle  kind:  the  contrary,  however,  is 
evinced  in  the  preceding  note. 


c  155-  ] 

thought  to  be  the  acid  of  common  fait  united  with 
a  fmall  portion  of  phlogifton. 

Infects,  fith,  and  vegetables,  are  often  found  in 
cluded  in  it,  which  teftify  its  having  once  been 
liquid.  ,  ,  ?••..:. 

It  is  more  transparent  than. moil  of  the  other 
bitumens ;  and  is  doubtlefs.  the  fubftance  which 
fir  ft  gave  rife  to  eleSrical  experiments  (on  account 
of  the  power  it  poifeffes  of  attracting  little,  bits 
of  ftraw,  or  of  other  light  fubltances,  when  rub 
bed). 

Its  variecies  are  reckoned  from  its  colour  and 
.  tranfparency.  It  it  is  found, 

A.  Opaque. 

a.  Brown. 

b.  White. 

c.  Blackifh. 

B.  Tranfparent. 

a.  Colourleis. 

b.  Yellow. 

The  greateft  quantity  of  European  amber  is 
found  in  Pruffia ;  but  it  is,  befides,  collected  on 
the  fea-coaft  of  the  province  of  Skone,  and  at 
Biorko  ;  in  trie  lake  Malaren  in  the  province  of 
Upland  ;  as  alfo  inFrarice  and  in  Siberia.  It  is 
chiefly  employed  in  medicine  and  for  making  var- 
niflies  (D). 

VII. 


.  (D)  Amber,  fays  M.  Fourcroy,  is  found  in  fmall 
detached  pieces,  for  the  mod  part  under  coloured 
fands,  difperfed  in  beds  of  pyritaceous  earth  ;  and  a- 
bove  it  is  found  wood,  charged  with  a  blackifh  bitumi 
nous  matter.  Hence  itJs  ftrongly  fuppofed  that  it  is 
a  refmous  fubftance,  which  has  been  altered  by  the 
vitriolic  acid  of  the  pyrites,  not  with  {landing  that  we 
know  that  acids,  when  concentrated,  always  blacken 

and 


C    '56    ] 

VIL  Rock-oil. 

This  is  an  inflammable  mineral  fubftance,  or  a  thin 
bitumen,  of  a  light  brown  colour,  which  cannot 
be  decompofed  ;  but  is  often  rendered  impure  by 


and  charry  refmous  fubftances.  In  faA,  the  chemical 
analyfis  of  this  fubftance  rather  confirms  that  fuppo- 
fition. 

The  fmgular  opinion  of  Dr  Girtanner,  about  the 
yellow  amber  being  produced  by  a  kind  of  ants,  may 
be  feen  in  Journal  de  Phyftque  for  March  1786,  page 
227.  Or  fee  the  article  AMBER  in  this  Dictionary. 

The  colour,  texture,  tranfparercy,  and  opacity  of 
this  fubftance,  have  {hown  fome  other  varieties  befides 
thefe  mentioned  in  the  text.  The  principal  ones  are 
the  following : 

6.  The  yellow  fuccinum, 

7.  The  coloured  green  or  blue  by     Q        Je< 
foreign  matter.  ^ 

S,  The  veined  fuccinum, 
9.  The  white,  "1 

10.  The  pale.yellow,       f 

11.  The  citron-yellow,    f 

12.  The  deep-red,          J 

The  golden  yellow  tranfparent  amber,  mentioned  in 
the  text,  is  what  the  ancients  called  chryfikarum,  and 
the  white  opaque  was  called  leucoledrum. 

But  we  muft  be  cautious  about  the  value  of  the  fpe- 
cimens  remarkable  for  their  colour,  fize,  tranfpaYen- 
cy,  and  the  well-prcferved  infects  they  contain  inter 
nally ;  fmce  there  is  a  probability  of  deception,  feveral 
perfons  pofTefling  the  art  of  rendering  it  tranfparent  and 
coloured,  and  of  foftening  it,  fo  as  to  introduce  fo 
reign  fubftances,  &c.  into  it  at  pleafure. 

M.  Fourcroy  fays,  that  two  pieces  of  this  fnbftance 
may  be  united,  by  applying  them  to  one  another,  af 
ter  being  wet  with  oil  of  tartar  and  heated.  And 

Wallerius 


\ 


[     '57     ] 

heterogeneous  admixtures.  By  length  of  time  it 
hardens  in  the  open  air,  and  then  refembles  a  ve 
getable  refin  ;  in  this  ftate  it  is  of  a  black  colour, 
whether  pure  or  mixed  with  other  bodies.  It  is 
found, 
A.  Liquid. 

1.  Naphtha. 

This  is  of  a  very  fragrant  fmell,  transparent, 
extremely  inflammable,  and  attracts  gold.  It 
is  collected  on  the  fur  face  of  the  water  in  fome 
wells  in  Perfia.  See  NAPHTHA. 

2.  Petrol. 

This  fmeils  like  the  oil  of  amber,  though 

more  agreeable  ;  andlikewife  very  readily  takes 

tire.     It  is  collected  in  the  fame  manner  as  the 

P  Naphtha 


Wallerius  mentions,  thnt  pieces  of  yellow  amber  may 
be  foftened,  formed  into  one,  and  even  diffolved  by 
means  of  oil  of  turnip-feed,  in  a  gentle  heat ;  and 
that  according  to  fome  authors,  it  may  be  rendered 
pure  and  tranfparent,  by  boiling  it  in  rape-feed  oil,  lin- 
leed  oil,  faltwater,  Sec. 

Mr  Macquer  fays,  that  for  the  purpofe  of  making 
varnifh,  this  iubftance  mull  undergo  beforehand  a  pre 
vious  decompoiition  by  torrefaction,  in  order  to  be 
diiiblved  by  linfeed-oil  or  eifential  oils.  S^e  VARNISH. 

Befides  the  making  of  varnifhes,  this  fubltance  was 
much  employed  formerly  in  making  various  pieces  of 
ornament  and  jewellery.  The  beft  pieces  were  cut, 
turned,  carved,  or  plained,  to  make  vafes,  heads  of 
canes,  collars,  bracelets,  muff-boxes,  beads,  and  o- 
ther  toys,  frnall  tine  chefts,  Sec.  But  after  diamonds 
and  beautiful  hard  ftones  were  brought  into  ufe, 
thefe  trinkets  are  little  coniidered  in  Europe  :  never- 
thelefs,  they  are  ftill  fent  to  Perfia,  China,  and  to 
various  other  eaftern  nations,  who  efteem  them  dill 
as  great  curiofities. 


C     >J8     ] 

Naphtha  from  feme  wells  in  Italy.     See  PE 
TROLEUM. 

J5.  Thick  and  pitchy  ;  Petroleum  tenax.     Barbadoes- 
tar. 

This  reiembles  foft  pitch. 

It  is  found  at  the  Dead  Sea  in  the  Holy  Land  ; 
in  Perfia,  in  the  chinks  of  rocks,  and  in  ftrata  of 
gypfum  and  limeftone,  or  floating  on  water  ;  al 
to  in  Siberia,  Germany,  and  Switzerland,  in 
coal-pits :  and  in  America :  likewife  in  Cole- 
brookdale  in  England. 
C.  Elaflic  petrol. 

This  is  a  very  fmgular  foffil,  found  of  late  in 
England. 

By  its  colour  and  confiftency,  it  exactly  refem- 
bles  the  Indian -rubber,  or  the  gum-refin,  from 
the  north  part  of  Brafil,  called  caoutchouc.  It  is 
of  a  dark  brown  colour,  almoft  black  ;  and  fome 
is  found  of  a  yellowifh  brown  caft,  like  the  fame 
gum-refin. 

With  refpecl  to  its  elaflic  confidence,  it  hard 
ly  can  be  diftinguifhed  from  it,  except  in  the  co- 
hefion  of  its  particles,  which  is  weaker. 

It  has  the  fame  property  of  rubbing  off  from 
paper  the  traces  of  black-lead  pencils. 

It  burns  likewife  with  a  fmoky  flame  ;  and  alfo 
melts  into  a  thick  oily  fluid ;  but  emits  a  difa- 
greeable  fmell,  like  the  foffiie  pitch,  or  Barba- 
dpes  tar. 

It  is  found  in  the  fame  earthy  and  ftony  beds 
as  petrol.  Some  fpecimens  are  of  a  cylindrical 
form,  like  bits  of  thin  branches  or  ftalks  of  vege 
tables,  though  much  more  flexible,  being  perfect 
ly  elaftic. 

M.  Magellan  obferves,  that  this  foffil  feems  to 
favour  the  opinibn  of  thofe  mineralogifts,  "  who 
believe  that  thefe  oily  combuftibles  derive  their 
origin  from  the  vegetable  kingdom.  It  feems 

worth 


C     '59     ] 

worth  trying,  whether  pieces  of  afphaltum,  bu 
ried  in  damp  beds  of  fparry  rubbifh,  or  other  kind 
of  earths,  would  take  the  fame  elaftic  confiftence. 
But  fince  many  beds  of  fhells  and  other  foffile 
fubftances,  both  of  the  vegetable  and  animal  kind, 
as  impreflions  of  various  plants,  and  the  remains 
of  various  quadrupeds,  &c.  have  been  found  in 
different  parts  of  the  globe,  whofe  individual 
fpecies  undoubtedly  exift  no  longer  alive  unlefsin 
far  diftant  climates,  and  in  the  mod  remote  coun 
tries  from  the  fpot  where  their  exuvia  are  dug 
cut ;  why  fhould  we  not  allow  that  this  new  foffil 
may  be  the  fame  original  elaftic  gum,  now  grow 
ing  naturally  in  Brafil,  China,  and  other  hot  cli 
mates,  only  altered  in  its  fmell,  and  in  the  tena 
city  of  its  particles,  by  its  long  depofition  during 
centaries  in  the  bowels  of  the  earth  ?" 

This  elaftic  petrol  was  found  in    1785,  near 
Caflfel-town,  in  the  county  of  Derbyfhire  in  Eng 
land,  but  in  very  inconfiderable  quantities, 
D.  Hardened  rock-oil ;  foffile  pitch.     Petroleum  in* 

duratum,  Plx  montana, 
j.  Pure  afphaltum. 

This  leaves  no  allies  or  earthy  fubftance  when 
it  is  burnt. 

It  is  afmooth,  hard,  biittle,  inodorous,  black 
or  brown  fubftance.  When  looked  through  in  fmall 
pieces,  appears  of  a  deep  red  colour.  It  fwims 
in  water. 

It  breaks  with  a  fmooth  finning  furface. — 
Melts  eafily :  and,  when  pure,  burns  without 
leaving  any  afhes  ;  but  if  impure,  leaves  alhes  or 
a  flag. 

According  to  M.  Monet,  it  contains  fulphur,  or 
at  leaft  the  vitriolic  acid. 

It  is  flightly  and  partially  afted  on  by  alcohol 
and  asther. 

P  2  From 


t  1 60  ] 

From  tliis,  or  the  preceding  fubftance,  it  is  pro 
bable  the  afphaltum  was  prepared  that  the  Egyp 
tians  ufed  in  embalming  their  dead  bodies,  and 
which  is  now  called  mummia. 

It  is  found  alfo  on  the  fhores  of  the  Red  Sea, 
in  the  Dead  Sea,  in  Germany,  and  France. — 
(  Kirwim , ) 

.And  it  comes  likewife  from  Poito  Principe,  in 
theifland  of  Cuba.  (Britn.) 

It  is  found  iilfo  in  many  parts  of  China  :   and 
is  employed  as  a  covering  to  ihips  by  the  Arabs 
and  Indians.      (Fourcroy,} 
a.  Impure ;  Fix  Montana  impura.     Pi/Taphaltnm. 

This  contains  a  great  quantity  of  earthy  mat 
ter,  which  is  left  in  the  retoit  after  diftilla- 
tion,  or  upon  the  piece  of  charcoal,  if  burnt  in  an 
open  fire  ;  it  coheres  like  a  flag,  and  is  of  the 
colour  of  black-lead  :  but  in  a  calcining  hsat, 
this  earth  quickly  volatiiiles,  fot&at  the  nature  of 
it  is  not  yet  kr.own. 

It  is  found  in  Moflgrufran  in  Norberg1,  and 
in  Grengierberget,  both  in  the  province  of  Weft- 
mainland  ;  and  alfo  in  other  places. 

The  piiTaphaltum  is  of  a  mean  confidence  be 
tween  the  afphaltum  and  the  common  petroleum. 
It  is  the  very  bitumen  which  is  collected  in  Au- 
vergne  in  France  in  the  well  called  de  la  Pegs,  near 
Ckrmcnt  Ferrand. 
VIII.  Jet.  Gffgas,  Sficcinum  mgnnn. 
•  This  is  a  very  compact  bitumen,  harder  than  afphal 
tum,  always  black,  and  fufceptible  of  a  good  po- 
lifli.  It  becomes  electrical  when  rubbed  ;  attraft? 
light  bodies  like  the  yellow  amber  ;  and  it  fwims 
on  water. 

It  feems  to  be  nothing  elfe  than  a  black  Jimber,  or 
fuccinum  ;  but  fpecifically  lighter,  on  account  of 
the  greater  portion  of  bitumen  that  enters  into  its 

ccmpo- 


[     161     ] 

compofkion.     When  burned,  it  emits  a  bitumi 
nous  Cm  ell.     See  the  article  JET. 
IX.  Mineralphlogifton  united  with  earths. 

A.  With  calcareous  earth. 

i.  With  pure  calcareous  earth.     This  is  the  fe 
tid  or  fwine  fpar  formerly  defer ibed. 

B.  United    with   calcareous,    argillaceous',  ponde 
rous,  and  (i  lie  eons  earth  and  vitriolic  acid.     Li- 
verftone  :   Lapis  hepdticus. 

C.  With  an  argillaceous  earth  ;   Pit  or  Stone  Coal. 

1.  With  afmall  quantity  of  argillaceous  earth  and 
vitriolic  acid.     LitLanthrax.     See  the  articles 
COAL  and  PIT-COAL. 

This  is  of  a  black  colour,  and  of  a  filming 
texture  :  it  burns  with   a  flame,  and  is  moftly 
confumed  in  th.ci  lire  ;  but  leaves,  however  a 
fmall  quantity  of  afnes. 
a.  Solid  coal.     b.   Slaty  coal. 

2.  Culm-coal,  called  kolm  by  the  Swedes. 

This  has  a  greater  quantity  of  argillaceous 
earth  and  vitriolic  acid,  and  a  moderate  propor 
tion  of  petrol. 

It  has  the  fame  appearance  with  the  preced 
ing  one,  though  of  a  more  dull  texture  :  it 
burns  with  a  flame ;  and  yet  is  not  confumed, 
but  leaves  Behind  a  flag  of  the  fame  bulk  or  vo 
lume  as  the  coal  was. 

From  England,  and  among  the  alum  rocks 
at  Moltorp  and  Biliingen  in  the  province  of 
Weftergottland. 

3.  Slate-coal. 

This  coal  contains  abundance  of  argillace 
ous  earth.  It  burns  with  a  flame  by  itlelf,  o- 
therwife  it  looks  like  other  dates. 

It  is  found  at  Gullerafen  in  the  parifli  of 
Rettwik,  in  the  province  of  Dalarne,  and  alfo 
with  the  coals  at  Boferupin  Skone. 

P3  This 


This  Teams  to  be  the  fame  with  the  bitumi 
nous  fchiftus,  already  defcribed  amon.g  the  ar 
gillaceous  earths. 
.  Canncl-coal. 

Mr  Kirwan  has  put  together  this  variety  of 
coal  with  that  other  called  KiUhnny-foal,  tho* 
they  have  fome  different  properties. 

The  cannel-coal  is  of  a  dull  black  colour  * 
breaks  eafily  in  any  direction  ;  and,  in  its  frac 
ture,  prefents  a  fmooth  conchoidal  furface,  if 
broken  tranfverfely. 

It  contains  a  considerable  quantity  of  petrol, 
in  a  lefs  denfer  irate  than  other  coals  ;  and 
burns  with  a  bright  lively  flame,  but  is  very 
apt  to  fly  in  pieces,  in  the  fire.  It  is  faid, 
rowever,  to  be  entirely  deprived  of  this  pro 
perty,  by  being  previously  immerfed  in  water 
for  fome  hours.  « 

Its  fpecific  gravity  is  about  1270;  and 
being  of  an  uniform  hard  texture  may  be 
eafily  turned  in  the  lathe,  and  receive  a  good 
polifh. 

It  is  from  this  kind  of  coal  thatfmall  vafec, 
as  ink-Hands,  various  trinkets,  and  other  curi- 
ofities,  are  made  in  England,  which  appear  as 
if  made  of  the  fineft  jet. 
Kilkenny-coal. 

This  contains  the  largeft  proportion  of  pe 
trol  or  afphaltum  ;  burns  with  lefs  flame  and 
{moke,  and  more  flowly.,.  though  intenfely,  than, 
the  cannel-coal. 

The  quantity  of  earth  in  this  coal  does  not 
exceed  one-twentieth  of  its  weight.  Its  ipe- 
cific  gravity  is  about  1400.  It  is  frequently 
mixed  with  pyrites. 

It  is  found  in  the  county  of  Kilkenny,  be 
longing  to  the  province  of  JLeinfter  in  Ireland. 
The  quality  of  this  coal  burning  almoil  with 
out 


[     163   J 

out  fmoke,   is  znentione4    in    a    proverb    bj 
which  the  good  qualities  of  that  country  are  ex- 
prefied. 
0-  .Sulphureous  coal. 

This  confifts  of  the  former  kinds  of  coal, 
mixed  with  a  notable  proportion  of  pyrites  : 
hence  it  is  apt  to  moulder  and  break  when  ex- 
pofed  to  the  air.  It  contains  yellow  fpots 
that  look  like  metal  ;  and  burns  with  a  ful- 
phureous  fmell,  leaving  either  red  afhes,  or  a. 
flag,  or  both.  Water  acts  upon  it,  after  it 
has  mouldered.  Its  fpeciftc  gravity  is  —  1500, 
or  more. 

Befides  the  above  varieties,  fchiftus,  mica 
ceous  fchiilus,  and  gneifs,  are  frequently  found 
in  the  neighbourhood  of  coal-mines,  fo  pene 
trated  with  petrol  bitumen  as  to  constitute 
an  inferior  fpecies  of  coal  ;  but  the  bitumen 
being  burnt,  they  prelerve  their  form,  and  in 
ft>me  meafure  their  hardnefs.  Alfo  fome  grey 
toes,  that  are  ib  foft  as  to  be  fcraped  with  the 
nail,  and  arc  greafy  to  the  touch,  burn  like  coal. 

All  the  differences  of  coal  arife  from  a  mix 
ture  of  the  varieties  already  mentioned  ;  and 
it  is  obfervable,.  that  wherever  coals  exift, 
Gates  are  generally  found  near  them.  Salt 
or  mineral  fprings  are  alfa  often  found  in  their 
tie  tghbourhaocL 


Bovey  coaL 

This  is  of  a  brown,  or  brownHh  black  co 
lour,  and  of  a  yellow  laminar  texture. 

The  larain.se  are  frequently  flexible  when 
£rll  dug,,  the  ugh  generally  they  harden  when 
expofed  to  the  air. 

It  confiils  of  wood  penetrated  with  petrol 
or  bitumen  ;  an.d  fi  equently  contauis  pyrites,  , 
,  and  .vitriol. 

Its  allies  afedrafmall  quaiuity  of  oxed  al- 


C    164    ] 

kali,  according  to  the  German  chemifts ;  but 
according  to  Mr  Mills,  they  contain  none. 

By  diftillation  it  yields  an  ill  fuelling  li- 
cmor,  mixed  with  a  volatile  alkali  and  oil,  part 
of  which  is  foluble  in  fpirit  of  wine,  and  part 
infufible,  being  of  a  mineral  nature. 

It  is  found  in  England,  France,  Italy,  Swif- 
ferland,  Germany,  Ireland,  &c.  (Kir wan.) 

8.  Peat.      Geaxtbrax. 

There  are  two  forts  of  inflammable  fub- 
(lances  known  by  this  name,  viz. 

The  fir  ft  of  a  brown,  yellowifh  brown,  or 
black  colour,  found  in  mooriih  grounds ;  in 
Scotland,  Holland,  and  Germany,  When 
freih,  it  is  of  a  vifcid  confidence,  but  hardens 
by  expofure  to  the  air.  It  confifts  of  clay 
mixed  with  calcareous  earth  and  pyrites  ;  and 
fometimes  contains  common  fait.  While  foft, 
it  is  formed  into  oblong  pieces  for  fuel,  after 
the  pyritaceous  and  ftony  matters  are  fepa- 
rated.  When  diftilled,  it  affords  water,  acid, 
oil,  and  volatile  alkali.  Its  afhes  contain  a 
frrjall  proportion  of  fixed  alkali.  They  are 
either  white  or  red,  according  as  it  contains 
more  or  lefs  ochre  or  pyrites. 

The  fecond  is  found  near  Newbury  in 
Berkfiiire.  It  contains  but  little  earth  ;  but 
confifts  chiefly  of  wood,  branches,  twigs, 
roots  of  trees,  with  leaves,  grais,  flraw,  and 
weeds.  ( Kir<wan. ) 

9.  Ctone-turf. 

Cronfteut  has  ranged  the  turf  among  the 
foflils  of  h,is  appendix  ;   but  as  that  called  in 
JEngland  by  the  name  of  fane-turf  contains  a 
•  Considerable  proportion  of  peat,  it  may  be  men 
tioned  with  propriety  in  this  clafs. 

Soon  after  it  is   dug  out  from  the  ground, 
where  it  keeps  a  foft  confidence,  it  at  firfl  har 
der,  s 


C    '65    'J 

liens ;  bnt  afterwards  it  crumbles  by  long  ex- 
pofure  to  the  air. 

As  to  the  other  common  tuirf,  it  only  con- 
fifts  of  mould  interwoven  with  the  roots  of 
veg-tibles;  but  when  thefe  roots  are  of  the 
bulbous  kind,  or  in  a  large  proportion,  they 
form  the  woril  kind  cf  turf. 

Although  it  may  appear  incredible,  it  is 
nevertheleis  a  real  fact,  that  in  England  pit-turf 
is  advantageoufly  employed  in  Lancafhire  to 
fmelt  the  iron-ore  of  that  county.  Mr  Wil- 
kinfon,  brother-in  law  to  Dr  Prieftley,  and  fa 
mous  for  his  undertakings  in  the  exteniive  iron 
works,  perhaps  the  greateft  in  Europe,  makes 
ufe  of  pit-turf  in  his  large  fmeldng  furnaces  of 
that  provim  e 

THOSE  foffil  fubitances,  which  furnifh  fuel  for  the 
various  purpofes  of  human  life,  are  diitinguiihed  by 
the  name  of  coals,  on  account  of  their  being  a  fucce- 
daneum  for  wood  and  other  vegetable  productions, 
which  when  dry  or  of  an  oleaginous  kind  ferve  for 
the  fame  ufes.  If  thefe  vegetable  fubftances  are  de 
prived  of  the  accefs  of  air,  by  covering  them  after  ig 
nition,  the  half  conlumed  remainder,  which  is  of  a 
black  colour,  is  called  by  the  name  of  coal  or  char- 
co-J. ;  and  from  hence  the  foflil  which  affords  fuel  has 
alfo  been  called  by  the  ia-me  name,  though  of  a  very 
different  nature. 

Pit-coal  and  earth-coal  are  fynonymous,  and  mean 
coals  dug  cut  of  a  pit  or  from  the  earth.  But  the 
lithanthrax  denotes  ftone-coal,  and  more  properly  in. 
dicates  the  cannel-coal,  which  has  the  greateft  firm- 
larity  to  a  ftony  fubftance,  by  the  dull  appearance 
of  its  fractures  and  by  the  uniform  texture  of  its 
parts. 

All  tkefe  coals  are  in  general  a  bituminous  black 
or  biown  and  dark  fubftance :  for  the  moil  part  they 

have 


C    166    ] 

have  a  lamellated  texture,  which  breaks  eafily,  and  al 
ways  with  a  fhining  furface. 

The  varieties  of  pit-coals  abovementioned  are  the 
moft  remarkable,  by  which  they  may  be  diftinguifh- 
ed  from  one  another.  But  they  are  far  from  being 
homogeneous  in  each  kind  ;  as  the  accidental  quali 
ties,  and  the  various  proportions  of  their  component 
parts,  produce  a  far  greater  number  of  properties, 
which  renders  them  more  or  lefs  fit  for  different  pur- 
pofes  ;  though  thefe  are  generally  overlooked,  and 
confounded  with  the  common  one  of  affording  fuel 
for  making  fire  to  warm  our  rooms,  or  for  culinary 
operations. 

This  foffile  bitumen,  as  Fourcroy  remarks,  being 
heated  in  contact  with  a  body  in  combuftion,  and  a 
free  accefs  of  air,  kindles  the  more  flowly,  and  with 
more  difficulty,  as  it  is  more  weighty  and  compact. 
When  once  kindled,  it  emits  a  brifk  and  very  durable 
heat,  and  burns  for  a  long  time  before  it  is  confumed.. 
If  eninguifhed  at  a  proper  time,  the  remaining  cin 
ders  may  ferve  feveral  times  for  a  new  firing  with 
a  fmall  addition  of  frefh  coals.  The  matter  that  is 
burned,  and  produces  the  flame,  appears  very  denfe, 
as  if  united  to  another  fubftance  which  retards  its  de- 
ftruclion.  Upon  burning,  it  emits  a  particular  ftrong 
fmell,  which  is  not  at  all  fulphureous  when  the  earth- 
coal  is  pure,  and  contains  no  pyrites. 

When  the  combuftible,  oily,  and  mod  volatile  parts, 
contained  in  the  earth-coal,  are  diffipated  and  fet  on 
fire  by  the  firft  application  of  heat ;  if  the  combuftion 
is  flopped,  the  bitumen  retains  only  the  moft  fixed 
and  leaft  inflammable  part  of  its  oil,  and  is  reduced  to 
a  true  charry  ftate,  in  combination  with  the  earthy 
and  fixed  bafe.  Pit-coals  in  this  charry  ftate  are  call* 
ed  coafa,  which  are  capable  of  exciting  the  moft  in- 
tenfe  heat ;  and  are  employed  all  over  Britain  in  the 
fmelting  of  iron,  copper,  and  other  metallic  ores,  to 

the 


t  ««?  i 

the    greatefl  advantage.      See  COAKS,  COAI,  COAL» 
ERY,  and  PIT-COAL  (E). 

X.  The 


(E)  The  coal-metals,  or  ftone  ftrata  inclofing  coals, 
are  very  numerous.  Mr  Wiliianis  f  gives  the  follow, 
ing  general  account  of  thofe  in  Scotland. 

"The  fand-ftones.  Of  thefe  there  is  a  great  Vari 
ety,  diftinguifhable  by  colour,  texture,  and  degrees 
of  hardnefs,  generally  difpofed  into  thick,  middling, 
and  thin  ftrata.  The  only  fpecies  our  author  takes 
notice  of  is  the  regular  broad-bedded  free-ftone  of  a 
laminated  texture.  This  commonly  rifes  in  thin  or 
middling  ftrata;  appearing  at  the  edges  of  a  fe&ion,, 
when  broken  or  cut,  to  be  formed  of  thin  lamina  or 
layers  of  fand,  equally  laid  on  the  whole  breadth  of 
the  ftone,  and  well  cemented  together.  A  great 
deal  of  both  red  and  white  free-Hone  rife  in  layers  of 
rive  or  fix  inches,  and  fo  upwards,  with  regular 
ftreaks  of  a  fifth  or  fixth  part  of  an  inch  appearing 
the  whole  length  of  the  ftone,  when  the  edge  of  a  llab 
is  polifhed,  as  if  fo  many  gentle  waves  of  water  had 
formed  the  layer.  The  regularity  of  the  ftruclure  of 
this  ftone  dorrefponds  exactly  with  the  regularity  of 
its  layers ;  and  our  author  is  of  opinion,  that  the  flag 
gy  grey-ftrata  of  free  ftone,  with  many  of  the  black 
and  grey-ftrata  of  coal  metals,  the  grey  flate,  as  well 
as  many  other  thin  ftrata  of  the  coal  metals,  may  be 
ranked  with  this  free  ftone  for  perfect  and  regular  ftra- 
tification. 

Along  with  thefe  he  clafles  fome  of  the  thin  argil 
laceous  ftrata.  "  Many  of  the  grey  regularly  ftrati- 
fied  mountain  limeftones  (fays  he)  are  alfo  ftreaked 
or  ftriped  ;  and  the  ftreaks  in  thefe  appear  more  con- 
fpicuous  when  broken  than  the  ftreaked  free  ftones. 
Some  of  the  hard  regularly  ftratified  mountain  rocks 

are 


i 


C      1 68     ] 

X.  The  mineral  phlogifton  or  bitumen,  united  with, 
the  vitriolic  acid  :  fulphur  or  brimftone.  Seethe 
article  SULPHUR. 

This 


are  alfo  ftratified  ;  and  in  all  thefe  three  kinds  of  ftones, 
the  ftreaks  are  regularly  and  exadly  parallel  to  the  bed 
of  the  ftone." 

Another  remarkable  inflance  of  regularity  of  ftrata 
i»  met  with  in  the  grey  flaggy  ftrata  of  Caithnefs. — 
Throughout  all  the  low  country  of  Caithnefs,  afquare 
of  about  10  or  15  miles,  there  are  bluiih  argillaceous 
flrata,  with  generally  a  fmall  quantity  of  lime  in  the 
competition  of  the  ftone,  which  is  indurated  to  a  grea 
ter  degree  than  is  common  to  fuch  thin  ftrata.  The 
ftone  is  ftrong  and  tough,  every  where  difpofed  in 
thin  broad-bedded,  regular  ftrata  ;  and  in  feveral  parts 
of  the  country  the  flags  are  fo  thin  and  regular,  and 
are  raifed  fo  light  and  broad,  that  they  are  ufed  for 
covering  houfes  ;  and  three  or  four  of  them  will  cover 
the  fide  of  a  fmall  one.  Our  author  mentions  a  gen 
tleman  who  has  an  eftate  on  the  fouth  fide  of  the  Pent- 
land  frith,  and  who  in  a  bay  there  raifes  flags  of  any 
fize  and  tbicknefs  he  pleafes ;  ««  fo  truly  flat  and 
fmooth,  that  he  has  only  to  iquare  the  edges  to  make 
of  them  good  loft  floors,  partitions,  chefts,  mangers, 
roofs  of  houfes  ;  in  flicrt,  he  does  every  thing  with 
them.  The  face  of  thefe  flags  are  as  fmooth  and  true 
a.  plane,  as  if  artificially  finilhed  by  the  beil  work 
man." 

In  mod  coal  fields  there  are  a  great  variety  of  ftrata 
of  different  kinds  accompanying  and  lying  between 
the  feams  of  coal,  of  all  forts  of  colours,  confiftencies, 
and  dimenfions;  all  of  them  blended  together  without 
any  certain  order  or  regularity  ;  fo  that  if  there  be  20 
feams  of  coal,  it  is  poflible  that  there  may  be  as  many 
different  roofs ;  that  is,  the  ftratum  which  is  the  iro- 
4  mediate 


t    171    3 

This  is  very  common  In  the  earth,  and  difcovers  it- 

lelf  in  many  an  1  various  forms.     It  is  found, 
A.  Native.     Sulphur  ttativum. 

In 


mediate  roof  of  one  feam  of  coal,  (hall  diifer  from  that 
of  another  feam  in  quality,  thicknefs,  and  colour,  fo 
that  perhaps  ao  two  of  the  twenty  Ihall  be  in  any  re- 
fpecl  alike. 

The  various  kinds  of  coal-roofs  (a)  commonly  met 
with  are  the  following. 

i.  Bafaltes.  This  is  very  common  in  Scotland, 
where  it  is  frequently  called  whin  ftone;  and  atBorrowf- 
tounnefs  there  are  feveral  thick  beds  of  it  between  the 
feems  of  coal.  One  of  them  being  the  immediate  roof 
of  a  ieam  of  coal  there  at  H'llhouie  lime  quarry,  there 
is  a  thin  feam  of  coal  beneath  a  beautiful  bed  of  colum 
nar  bafaltes.  In  the  Bathgate  hills  to  the  fouthward  of 
Linlithgow,  alfo,  there  are  feveral  ftrata  of  coal  blended 
with  thole  of  bafaltes.  Thefe  bafaltine  ftrata  are  always 
very  hard,  frequently  very  thick,  and  generally  cf  a 
black  or  blackifh  grey  colour;  "  there  are  but  few  people 
(fays  Mr  Williams)  fufficiently  verfecl  in  natural  hilto- 
ry,  to  know  that  they  are  bafaltes,  as  this  kind  of  rock, 
both  in  England  and  Scotland,  goes  by  the  name  of 
ivhln  rock,  In  the  north  of  Scotland  it  is  calledySzwv/y  / 
and  among  the  miners  in  Cornwall  it  has  the  name  of 
cockle  (/>)•"— 

(a)  The  ftratum  which  is  placed  immediately  above  a  feam 
of  coal,     is  called  the  roof  of  the  coal,  and  that  v.-'nich    is  placed 
immediately  below  the  feam,  is  called  the  pavement  of  the  coal  : 
which  three,  viz.   the  itratu;n   of  coal,   and  its    roof  and  pave 
ment,  with  the  other  concomitant  ftrata  lying;  above  and  below 
them,  always  prclorve    thoT  ftations  and   parallelling  ;  that  is, 
are  ail  fhotrhecl  out  and   fpread   one    above   another  upon  the 
fo.:r.o  inclining  plane,    aud  have  the  fame  line  of  bearing  and  of 
declivity. 

(b)  We  mufi  obferve,  however,  that  according  to  Bergman 
ar,d  other  eminent  imntralogifts,  the  cockles  or  ihirls  ought  net 

Q,  to 


I  172  J 

In  this  the  two  conftituent  parts  are  mixed 
in  due  proportion  in  regard  to  each  other,  ac 
cording  to  the  rules  of  that  attraction  which  is 
between  them.  It  is  eafily  known, 

i.  By 


2.  Strata  of  limeftone  of  various  thicknefTes  are  met 
'with  in  different   coal-fields.     Sometimes   the   lime  is 
the  immediate  roof;  but  fometimes  there  is  'an  argil 
laceous  ftratum   of  about  the   thicknefs  of  a  foot   be 
tween  the  coal  ftratum  and  that  of  lime.     In  the  coal 
fields  at  Gilmerton,  near  Edinburgh,  are  feveral  beds 
of  limeftone,  fome  of  them  very  good,  and  of  confide- 
rable  thicknefs.     At  Blackburn  in  Weft  Lothian,  alfo, 
there  is  a  ftratum  of  limeftone  fix  or  feven  feet  thick, 
Avhich  is  the  immediate  roof  of  a  feam  of  coal  about 
five  or  fix  feet  thick.     At  Carlops  and  Spittlehaugh  in 
T  weedale,  they  have  a  feam  of  coal  immediately  below 
their  lime  quarries,  which  they  work  for  burning  their 
lime. 

3.  Poft-jlone,  a  kind   of  thick  and    folid   ftratum  of 
free  ftone,  is  one  of  the  roofs  of  coal,  generally  with 
out    the    intervention  of   any    argillaceous    ftratum, 
though  f©metimes  a  ftratum  of  this   kind  is  inter  po- 
Icd.      Frequently  this  kind  of  ftone  is  rendered   very 
hard  by  a  mixture   of  iron  or   pyrites.     In  moft  coal 
fields,  thinner  ftrata  of  free  ftone  are  met  with  as  the 

roofs  of  coal  feems. 

4.  Dogger-land,  as  it  is  called  by  the  Scots  colliers, 
is  frequently  met  with  as  the  roof  of  coal  feams.    This 
name  is   applied  to  various   lubftances.     Sometimes 
they  call  ftrata  of  iron-ftone  dogger  bands  ;  fometimes 
the  name  is  reftricted  to  the  ball  iron-ftone  ;  fometimes 
to  pyrites ;  and  fometimes  the  dogger  band  is  a  kind 

of 

to  be  confounded  with  bafaltes;  w-hich  laft  name  does  not  at  all 
fit  thofe  iubftances.     fee  Volcanic  Pio«Ui&s  in  the  Appendix  to 

1  <his  article. 


E    173    1 

1.  By  its  inflammability,  and  by  its  flame., 

2.  By  its  fmell  when  burnt;  and, 

3- 


of  imperfect  ilone,  compofed  of  feveral  heterogeneous 
mixtures,  among  which  pyrites  bears  a  considerable 
proportion,  and  by  which  the  whole  is  fo  ftrongly 
bound  together,  that  it  is  frequently  very  difficult  to 
break  through'it. 

5.  Wi'mjtwSi  properly   fo  called,  not  of  a  bafallic 
nature.     Thefe  roofs  are  always  very  hard,  and  of  va 
rious  colours,  as    black,  blackilh    grey,  brown,  red, 
&c.  fometimes  not  above  two  or  three  feet  in  thkknefs, 
but  fometimes  much  more. 

6.  PQJl-jione)  of  a  fofter  nature  than  that  already 
mentioned.     This  has  no  mixture  of  ferruginous  mat 
ter. 

7.  Regular Jlrata  offree-jlone,  of  various  colours,  tex 
tures,  and  thickneiTes,  but  not  fufficiently  thick  to  de- 
ferve  the  name  of  poftjlone,  which  our  author  thinks 
they  do  not,  unlefs  they  are  above  three  or  four  feet. 
Thefe  thin  flrata   of  free  (tone  are  very  numerous  in 
coal  fields,  and  very  frequently  form  the  roofs  of  ccal- 
feams.  Some  of  them  are  three  or  four  feet  thick,  while 
others  do  not  exceed  three  or  four  inches.     They  make 
good  roofs,  eafily   cut  through,,  and  may  be  readily 
quarried  out  for  other  purpofes. 

8.  Grey-bands,  or  grey-coloured  free- (tone,  frequent 
ly  form  the  roofs  of  coal  feams.     A  great  number  of 
them  are  generally  arranged  in  one  place,  lying  imme 
diately  above  one  another;  and  they  .are  frequently 
found  of  all  degrees  of  thicknefs  from  one  to  twenty 
inches,  though  the  mod  common  dimenfions  are  from 
two  to  fix.     By  the  Scots  colliers  thefe  are  called  grey 

fekes  as  well  as  grey  bands.    Frequently  they  are  found 

of  moderate  hardnefs,  and  fufficiently  ftrong  to  make 

good  flags  and  covers  for  fev/ers.     Thefe  roofs  are 

Q_2  ftrong 


C    '74    ] 

By  its  producing  a  liver  of  fulphur,  when 
mixed  w;th  a  fixed  alkali,  like  that  made 
from  artificial  fulphur.  It  is  found, 

a.  Pellucid 


ftrong  and  fafe  when  the  ftone  partakes  of  the  nature 
of  the  coal,  and  has  a  black  or  blackiili  grey  colour  j 
but  when  they  have  a  mixture  of  tilly  or  argillaceous 
matter,  they  are  more  friable. 

9.  Blaes,  when  hard,  ftrong,  and  well  Gratified,  are 
reckoned  tolerably  good  coal-roofs.  Thefe  are  always 
of  a  bluifti-black  or  black-grey  colour,  and  are  of  great 
variety  m  refpecl  to  hardnefs  and  ftrength.  Some  of 
the  ftrongeft  and  hardeft  are  either  entirely  black  or 
greyifli  black;  while  iome  of  the  different  {hades,  of 
black  are  pretty  thick,  and  others  are  but  thin.  The 
thickeft,  however,  are  not  above  18  inches,  and  the 
thinneil  two  or  three  inches  or  lefs.  The  medium 
thicknefs  is  from  one  foot  to  three  or  four  inches.  Some 
of  them  are  furTiciently  hard  to  make  a  good  and  fafe 
coal-roof;  but  they  feldom  acquire  fuch  a  degree  of 
hardnefs  as  to  give  any  confiderable  obftruclion  in  fuck 
ing.  All  of  them  feem  to  have  a  confiderable  quantity 
of  black  argillaceous  matter  in  their  compofition  ;  and 
the  ftrong  blaes  have  alfo  a  confiderable  quantity  of 
jfand  ;  often  alfo  containing  a  large  portion  of  ernpy- 
reumatic  oil,  and  fometimes  have  a  confiderable  mix 
ture  of  coaly  matter.  There  is  a  great  variety  both  in 
the  thicknefs  and  quantity  of  rhtfe  blaes  found  above 
feani>  of  coal.  In  feme' places  the  thirncft  ftrata  make 
the  immediate  roof;  in  ethers,  the  th.ckcft.  Some 
times  we  find  only  five  or  fix  inches  of  blues  upon  the 
coal ;  in  others  as  many  fathoms,  or  even  much  more  ; 
and  it  is  common  to  find  them  of  all  the  intermediate 
thickness. 

I  o.  WklCtfb  and  ofa-colourcd argillaceous Jlrata,  of  mid 
dling  ftrength,  are  frequently  found  to  be  the  immedi 
ate 


[     '75  .  ] 

a.  Pellucid,  of  a  deep  yellow  colour. 

b.  Opaque,  white,  and  greyila. 

Thefe 


ate  roofs  of  coal.  Some  of  thefe  are  of  middling 
thicknefs,  others  thin..  They  are  commonly  fouiul 
from  two  inches  to  two  feet  in  tlucknefs.  A  great  ma 
ny  of  thefe  roofs  are  very  dangerous  on  account  of 
their  fragility  ;  while  others  are  quite  fafe,  owing  to 
the  more  perfect  formation  of  their  ftrata,  or  t3  fome 
ingredient  in  their  composition. 

ii.  Streaked  roofs.  Thefe  are  of  two  {bits  :  i.  Such 
as  are  compofed  chiefly  of  land,  with  a  very  fro  all 
mixture  of  clay  and  blaes ;  and,  2,  Thofe  compofed 
principally  of  clay  or  blaes  with  a  fmall  quantity  of 
fand.  Some  of  thefe  have  large,  others  i'mall,  ftreak-i 
or  ribs.  Mr  Williams  fays  that  he  has  feen  them  ib 
beautifully  ftreaked  as  to  refemble  the  fineft  ftriped 
cotton  fluffs.  Thefe  ftripes  or  ftreiaks  always  lie  ex 
actly  parallel  to  one  another,  as  well  as  to  the  bed  of 
the  ftone,  and  are  always  fpread  out  the  whole  bread; h 
of  the  ftratum.  Their  colours  are  various  in  d.ffcrent 
ftrata.  fome  of  the  iiripes  being  nearly  bl  ick  and  white:, 
others  v/hite  and  red,  and  others  yellow  and  red.  In 
fome  the  ftripes  appear  of  a  lighter  and  darker  grey 
colour.  Some  of  the  finely  ftriped  Hones  have  thtir 
about  a  quarter  cf  an  inch  in  diameter  ;  fome* 
t'mes  ids :  an-.l  it  is  con:nyon  to  fee  (tripes  from  a  quar 
ter  to  three  quarters  of  an  inch  broad  ;  but  in  the  fine 
ly  ftriped  Hones  it  is  rare  to  find  them  a  full  inch  thick 
without  fome  different  iuade  on  one  fide  or  other  of 
the  ftripe.  The  fscond  kind  of  thefe  ftreaked  roofs, 
viz.  fuch  as  are  compofed  of  blaes,  with  a  fmaller  mi?:- 
tuie  of  fand,  differ  but  litth  from  the  former  ;  only  the 
colours  are  r.ot  always  fo  bright,  nor  ;he  ft:  «pes  fo  fine  j 
neither  is  the  roof  quite  fo  hard. 

I*-   Tf* 


[     J76  I] 

Thefe  are  found  in  Siberia,  at  Bcvieux  m 
Swiiferland,  and  at  Solfatara  near  Naples. 
c.  Cryftallifed  in  octoedral  prifms,  with  blunted 
points. 

d.  Tranf- 


12.  The  foft  I lae  roqfs  frmetimes  confift   of  pretty 
thick  ftrata ;  others  of  fuch  as  are  thin  or   ef  mid 
dling  thicknefs.     There  are  likewife  arrangements  or 
dalles  of  regularly  ftratified  blaes,  found   immediate 
ly  above  feams  of  coal,  from  three  or  four  inches  to  fe- 
veral  fathoms  in  thicknefs,  though  forne  are  even  met 
•with  little  exceeding  one  inch  in  thicknefs  ;  though  in 
trie  fame  place  there  might  be  a    confiderabls  thick 
nefs  of  blaes  above  the  coal,  taking  in  all  the  different 
ilrata,  thick  and   thin,  which  lay  above  it.     Some  of 
thefe  roofs  have  an  oily  appearance  on  the  outfide,  and 
through  all  the  fiifures  and  joints  of  the   ftrata  ;  that 
is,  they  appear  fmooth  and  gloffy,  and  are  very  ilip- 
pery  to  the  tench.     Others  have  no  appearance  of  this 
kind  ;  but  all  of  them  are  tender,  weak,  and  fragile, 
fo  that  they  make  a  very  indifferent  and  dangerous 
roof. 

13.  Another  kind  of  coal-roof  confifb  likewife  o£ 
l*/aes,  but  fuch  as    are    'r.nperfe8ly  jlratijied.      It  is  alto 
gether  the  fame  in  quality  and  colour  as  the  laft,  the 
only  difference  that  can  be  diftinguiihed  being  in  the 
diiFcrent  degrees  of  Gratification.     The  beds  of  this 
kind  are  not  perfect,  but  unequal ;  whence  it  is  a  bad 
and  dangerous  roof,  as  great  pieces  of  it  are  frequent 
ly  apt  to  fall   down   by  reafon  of  the  inequality  and 
ditlorent  joints  of  the  ftrata.     Some  of  thefe  blaes  ap 
pear   in  thick,  and  others  in  thin  or  middling  thick 
beds :  while  fome  have  an  oily  fmoothnefs,  called  by  the 
Scots  colliers  crcefky  (greafy)  blaes.      It  is  owing  to  this 
oilinefs  particularly  that  thefe  kinds  of  roofs  are  fo  danr 
gerou$%;  for.  the.  oil  pervad.es  the  joints,  and,  icnder- 


C    177    1 

Tranfparent.  Mr  Davila  had  been  informed 
that  this  was  brought  from  Normandy  in 
France.  (Brim.) 

2.  Native 


ing  them  flippery,  makes  the  pieces  more  apt  to  fall 
out  as  loon  as  the  coal  is  worked  away  from  below 
them.  Some  of  thefe  have  fuch  a  quantity  of  natural 
oil,  that  they  will  flame  a  little  in  the  fire ;  and  in 
fome  places  there  are  hard  blaes  which  will  burn  when 
fire  is  let  to  them,  though  they  will  not  confume.  At 
Pitfirran  in  Fitefhire  there  is  a  fpecies  of  thefe  blaes  fo 
inflammable,  that  when  fire  is  fet  to  one  corner  of  a  hil 
lock  it  will  burn  throughout  the  whole  ;  neverthelefs  it 
is  not  reduced  in  bulk  by  this  combuftion,  nor  does  it 
produce  any  afhes.  Inilead  of  this  it  becomes  confidc- 
rably  harder  than  before,  and  acquires  a  pale  red  co 
lour.  By  reafori  of  its  hardnefs,  it  is  proper  for  being 
laid  upon  horfe  and  foot  paths,  but  is  not  fo  for  roads 
over  which  heavy  wheel-carriages  pafs. 

14.  Soft  blaes  not  jlrat'ified  at  all.  Of  thefe  there  is  no 
more  than  one  bed  from  two  or  three  inches  to  feveral 
fathoms  in  thicknefs,  without  any  others  either  above 
or  below  it.  They  are  as  common  as  any  above  the 
coal  feams ;  but  their  fubftance  is  not  always  uniform 
throughout  the  whole  ftratum.  Some  of  them  are 
found  divided  into  fmall  angular  maffes,  and  others  in 
to  larger  ones  ;  but  whether  thefe  are  uniform  or  net, 
they  always  make  a  bad  and  dangerous  roof.  Thefe 
argillaceous  ftrata  are  fometimes  called  beds  of  till ;  the 
uniform  fort  are  called  dauky  and  the  glebous  kir 
blaes,  by  the  Scots  colliers.  Both  the  uniform  and  gle 
bous  fo  ft  blaes  frequently  contain  a  quantity  of  ball 
iron-done,  though  fome  of  it  contains  none  at  ail. 
The  regular  continuous  itrata  of  ironstone  are  com- 
aionly  found  in  ftratifisd  foft  blaes.  There  is  a  varior 


C    178    ] 

Native  fulphur  is  found  in  different  forms, 
wa.  either  in  folid  pieces  of  indeterminate 
figure,  running  in  veins  through  rocks ; 
or  in  fmall  lumps,  in  gypfum  and  lime- 

ftones ; 


ty  of  foft  coal  roofs  of  a  grey  odour,  and  of  which 
fome  are  regularly  ftratified,  and  fome  not. 

1 5 .  Regularly  J'jft  grey  coal-roofs. — Of  thefe  there  are 
feveral  forts.     Some  have  a  confiderable  quantity  of 
fand  in  the  composition   of  the  ftrata ;  and  many  of 
thefe  are  as  regularly  ftratified   as    any  coal-metals 
\vhafever.     Numbers  are  found  very  thin,  and  others 
of  middling  thicknefs  ;  though  in  all  cafes  they  are  fo 
tender  and  friable,  that  they  make  very  bad  and  dan 
gerous  roofs.     Some  of  them  indeed  look  pretty^  well 
;it  fir  ft  ;  but  they  foon  crumble  and  comedown,  efpe- 
cially  when  they  have  been  expofed  to  the  air.     This, 
in  the  opinion   of  Mr  Williams,  is  owing  partly  to 
their  having  too  much  clay  in  their  compofition,  aiid 
partly  to  the  want  of  a  fufficient  quantity  of  natural 
cement  to  connect  the  feveral  particles  of  the  ftune  to 
gether. 

16.  Soft  grey  regular  f}rata>  or  grey  bands  of  an  ar 
gillaceous 'kind  ;  and  of  thefe  there  is  likewife  a  con- 
iiderable  variety.     Some  are  of  a  dark,  others  of  a 
lighter  grey  ;  feme  thick,  others  thin  :  they  are  very 
numerous  in  coal-fields,  and  are  frequently  to  be  found 
as  the  immediate  roofs  of  coal.     Thefe,  as  v/ell  as  the 
black  kinds,  are  found  ia  all  quantities  or  degrees  of 
thicknefs  above  different  coals,  from  a  few  inches  iip 
to  feveral  fathnms  ;  but  whether  they  be  in  great  cr 
fmall  quantity,  the  roof  they  compofe  is  generally  very 
frail  and  tender. 

17.  Soft  grey  argillaceous  lands,    mpsrfeflly  ftraiijicd. 
Thefe  differ  little   or  nothing  in  fubftance  from   the 
former;    the  only   difference   is  in  the    {^ratification. 

Many 


ftones ;  in  confiderable  quantities  at  Sol- 
fatara,  and  in  the  neighbourhood  of  vol 
canoes  ;  or  cryftallifed  in  pale,  tranfparent, 
or  femitranfparent,  octogonal,  or  rhom- 

boidal 


Many  of  the  flrata  of  the  former  are  of  a  middling 
thlcknefs,  or  rather  thin,  finely  and  regularly  fpread 
out,  and  every  part  of  each  ftratum  of  an  equal  thick- 
nefs.  But  this  fort,  though  it  has  the  appearance  of  ftra- 
ta,  is  clumfy  ah4  irregular  ;  that  is,  the  feveral  beds 
are  unequal,  and  divided  by  many  irregular  joints  in 
to  unequal  miihapen  mafles,  which  makes  this  a  very 
bad  roof;  the  maffes  being  apt  to  feparate  at  the 
joints,  and  to  fall  down  when  the  coal  is  worked  out 
from  below  them. 

1 8.  Soft  grey  argillaceous  led*  of  metal  or  coal  roofs 
notjlratified  at  all.     Thefe  are  of  two  kinds,    viz.  x. 
fuch  as  are   found  broken  or   formed  in  the  ftratum 
into  glebes  or   mafles  ;  and,  2.  fuch  as  are  found  in 
one  ujiifojrm  mafs  throughout  the  whole  bed,  without 
any  dtvifion  into  maffes   or  ft  ata.     Thefe  grey  foft 
roofs  are  of  all  degrees  of  thicknefs,  from  a  few  inches 
up  to  many  fathoms,  as  well  as  the  black ;  and  there 
is   but  very  little  difference  between  them  in  any  re- 
fpecl  excepting  the  colour.     Eat  in  this,  .is  well  as  in 
the  black  unftmtified  blaes,  and  th.it  both  in  the  gle. 
bous   and  uniform  beds,  ball  or  glebnus  iron-done  is 
frequently  found  ;  and   ftrata  of   iron-itone  are  alfo 
found  in  the  ftratified  foft  grey  blaes. 

1 9.  White  and  afo-cohured  foft  argillaceous  ccal  roofs  ; 
and  of  thefe  there  is  alfo  a  great  variety.     Some  of 
this  kind  are  regularly  ftratified?  others  imperfectly, 
and  fome  not  at  all.     Some  of  the  whitifh  argillace 
ous  roofs  are  compounded  of  gritty  fand  and  clay ; 
others  appear  to  be  chiefly  compofed  of  pure  clay  ; 
and  fome  of  a  loamy  clay.      Thofe  which  are  regu 
larly 


boidal  cryftals,  in  the  cavities  of  quartz  ; 
and  particularly  in  the  matrices  of  ores  ; 
or  in  the  form  of  fmall  needles  over  hot 
fprings,  or  near  volcanoes  (Kirwan). 

Sometimes  it  is  formed  in  old  privies  : 
cf  this  Mr  Magellan  faw  feme  Jumps  that 
were  found  in  a  very  old  one  at  Paris. 

2.  United 


larly  flratified  and  mixed  with  fand,  either  coarfe  or 
fine,  are  of  great  variety  with  regar4>o  thicknefs  and 
the  arrangements  of  the  ftrata  ;  htft'all  of  them  are 
tender  and  fragile,  and  thus  make  very  troublefome 
and  dangerous  roofs. 

20.  Wkiiifk  argillaceous   roofs,  Jlrai'tfed,  and  of  a  ho 
mogeneous  quality,  or  not  mixed  with  fand.     Some 
of  thefe  are  finely  and  perfectly  ftratified,  and  are  of 
different   degrees  of  hardnefs;  but  in  general,  make 
but  a  weak  roof.     Some  of  them  are  found  in  irregu 
lar  ftrata,  with  all  the  other  varieties  and  imperfedi- 
ons  already  mentioned. 

21.  Wilts  and  ajlo- coloured  argillaceous  coal-roofs,  not 
jlrat\fi.cd  at  all.     Sometimes  thefe  are  found  in  'Very 

thick  beds  in  the  coal-fields  ;  and  fomc  of  thefe,  as  well 
as  of  the  black  foft  roofs,  rife  in  glebes  and  rnafles  of 
different  fizes ;  while  others  are  homogeneous  through 
out  the  whole  bed,  however  thick,  from  two  or  three 
inches  to  feveral  fathoms.  Some  of  thefe  beds  of  white 
argillaceous  mark-like  matter  are  found  to  be  a  fancly 
or  loamy  clay ;  others  a  pure  homogeneous  clay, 
which  does  not  feel  gritty  between  the  lingers  nor  in 
the  mouth.  The  iliades  and  varieties  of  this  kind  are 
as  numerous  as  thofe  of  any  of  the  foregoing ;  and 
all  of  them,  by  the  Scots  colliers,  are  called  dau&, 
whatever  be  thein colour.  Mr  Williams  informs  us, 
that  he  has  frequently  taken  fome  of  thefe  fine  white 
clays  to  waOi  his  hands,  and  has  found  them  anfwey 
almoft  as  well  as  foap. 


2.  United  with  clay  in  the  aluminous  ore 
of  La  Tolfa,  and  alfo  at  Tarnowitz  in 
Silefia.     This  laft  refembles  a  li;-at  grey 
earth  :   when  dry,  burfts  or  cracks  in  the 
wat.rlik:  rmrle  ;  and  poffeffes  a  ftrong 
peculiar  fmeli  1'ke  camphor.     If  diftilled, 
the  fulphur  fuhlimes.     One  hundred  parts 
of  *his  earth  afford  eight  of  fulphur,  be- 
fides  gypfum  and  a  quantity  of  iron. 

3.  Mixed  with  clay,  iron,  and  felenite.  This 
compound  is  of  a  grey,  brown,  or  black  co 
lour,  found  near  Rome,  Auvergne,  Spain, 
and  Iceland. 

4.  With  limeftone  in  the  form  of  a  calcare 
ous  hepar.     This  is  found  at  Tivoli,  near 
Rome,  and  ellewhere  in  Italy.  It  is  fome- 
times  diflblved  in  mineral  waters,  three 
pounds  of  which  contain  as  much  as  25 
grains  of  fulphur.     It  often  forms  incruf- 
tations  on  the  brinks  of  thefe  Iprings. 

5.  In  the  form  of  an  alkaline  hepar.     This 
is  faid  to  be  found  in  fome  waters  in  Ruf- 
fia  ;  as  will  be  hereafter  noticed. 

6.  United  to  iron  and  clay  of  pyrites,  -&c. 
of  which  hereafter. 

7.  United  to  metallic  fubftances,  as  hereaf 
ter  fpecified. 

J5.  Saturated  with  metals  (F). 

I.  With  iron.  Pyrites,  or  copperas-ftone  ;  Py 
rites.  This  is  the  fubftance  from  which  moil 
fulphur  is  prepared,  and  is  therefore  ranked 

here 


(F)  Sulphur  is  the  mod  common  mineralifer  of  me 
tals ;  and  therefore  moft  of  its  combinations  with 
thofe  fubitances  fall  to  be  ranked  hereafter  among  the 
metallic  ores. 


t    i**    3 

here  with  all  its  varieties.     It  is  hard,  and  of  a 
metallic  fhining  colour. 

A.  Pale  yellow  pyrites  ;  Pyrites  Julflavus.  Mar- 
cafite.     This  is  very  common,  and  contains 
a  propoitionable  quantity  of  fulphur  with 
refpect  to  the  iron  ;  when  once  thoroughly 
inflamed,  it  burns  by  itfelf. 

a.  Of  a  compact  texture;  Pollta  piedra  del 
ynca,  Htfpanoruin. 

b.  Steel-grained. 

c.  Coaiie-grained. 

d.  Cryftallifed.     It  {hoots  moftly  into  cubi 
cal  and  octoedral  figures,  though  it  alfo 
cryftallifes  into  innumerable  other  forms. 

B.  Liver-colt  ured  marcafite.     Its  colour  can 
not  be  defcribed,  being  betwixt  that  of  the 
preceding  marcafite  and  the  azure  copper 
ore.     The  iron  prevails  in  this  kind  ;  it  is 
therefore  lefs  fit  to  have  fulphur  extracted 
from  it,  and  alfo  for  the  fmelting  of  copper 
ores.      It  is  found, 

a.  Of  a  compact  texture. 

b.  Steel-grained. 
f.  Goalie-grained. 

o  Variously  combined  with  iron  and  other  metallic 
fubftances. 

1.  With  iron  and  copper;  forming  yellow  or 
marcafitical  copper  ore. 

2.  With  iron,  lilver,  and  lead  ;  potters  lead  ore. 

3.  With  iron  and  zinc  ;  mock  lead,  black  jack 
or  blende. 

4.  With  iron  and  arfenic  ;  arienical  pyrites. 

5.  With  iron  and  cobalt. 

6.  With  iron  and  bifmuth. 

7.  With  iron  and  nickel. 

8.  With  iron  and  gold  ;  pyritical  gold  ore. 

9.  With  diver  ;  glafs  filler  ore. 

10.  With  copper  5  grey  cr  vitreous  copper  ore. 
i  1 1.  With 


11.  With  lead  ;  potters  lead  ore. 

12.  With  bifmuth. 

13.  With  quickiilver;  cinnabar. 

14.  With  arfenic  ;  orpiment,  realgar. 

XI.  Mineral  phlogilton  mixed  with  metallic  earths. 
•      This  is  not  found  in  any  great  quantity  :  in  regard 

to  its  external  appearance,  it  refembles  pit-coal ; 

and  the  fat  fubftance  contained  in  it,  at  times, 

partly  burns  to  coal,  and  partly  volatilifes  in  a 

calcining  heat. 
The  only  known  varieties  of  this  kind  are, 

A.  Mlncra  c upn  pbloglftlca. 

When  it  h'-is  been  inflamed,  it  retain?  the  fire, 
and  at  lafl  burns  to  allies,  out  of  which  pure 
copper  can  be  fmelted. 

B.  M'msra  fern phloy/Tica. 

This  is  not  very  different  in  its  appearance  from 
the  pit  coal  or  fotiile  pitch,  but  it  is  fome- 
what  harder  to  the  touch.  There  are  txvo  va 
rieties  of  this  fpecies  : 

1 .  Fixt  in  the  fire  ;  Mineraferri  pUogifllca  f.xa. 
Expofed  to  a  calcining  heat,  it    burns  with  a 

very  languid  though  quick  flame  ;  it  pre 
fer  ves  its  bulk,  and  lofes  only  a  little  of  its 
weight.  It  yields  above  30  per  cent,  of  iron. 

a.   Solid,  which  refembles  black  fealiag-wux. 

I.  Cracked,  and  friable. 

2.  Volatile  in  the  fire. 

This  is  unalterable  in  an  open  fire,'  either  cf 
charcoal,  or  even  upon  a  piece  of   charcoal 
before  the  flame  of  the  bio  v-pipe  ;  but  under 
a  muffle  the  greateft  part  of  it  volatilifss,  f  > 
that  only  a  fmall  quantity  of  calx  cf  iron  re 
mains.     It  is  found, 
a.   Solid. 
I-  Cracked. 

This  lad  kind  leaves  more  afaes :  thefe  aflie-, 

when  farther  expofed  to  the  fire,  become 

firil  yellowiih-grjen,  and  afterwards  red* 

R  difli 


C    184    1 

difh-brown  ;  when,  befides  iron,  they  then 
alfo  difcoverfome  marks  of  ccpf.er  :  it  has, 
however,  u<t  been  poffible  to  extr.cl:  any 
metallic  fubftance  from  them,  the  effects 
of  the  loadftone,  and  the  colour  ccmmuni- 
cated  to  the  glafs  of  borax,  having  only 
given  occafion  to  this  fufpicion. 

CLASS  IV.    METALLIC  SUBSTANCES. 

METALS  are  thrfe  minerals  which,  with  refpect  to 
their  volume,  are  the  heavieft  of  all  known  be  dies. 
Some  of  them  are  malleable;  and  fome  may  be  de 
compounded;  and,  in  a  melting  heat  (G),  be  brought 


(G)  The  various  degrees  of  heat  required  to  reduce 
metals  to  a  fluid  (late,  are  feen  in  the  following  table, 
which  was  extracted,  for  'he  moft  part,  by  Dr  Wither 
ing,  from  the  printed  treatifes  of  the  late  celebrated 
Profeflbr  Bergman.  It  exhibits,  in  a  fimple  view,  i. 
Tl'C  fpecific  gravity  of  each  metal;  2.  The  degree  of 
heat  by  Fahrenheit's  fcale,  in  which  it  melts ;  3.  The 
quantity  of  phlogiflon  it  requires  for  its  faturation  ;  and 
4.  Its  attraction  to  the  fame  faturatirig  pblogifton.  We 
mini,  however,  obferve,  that  if  the  feccnd  column 
bi  compared  with  that  of  Wedgwood's  thermometer, 
their  great difagreements  betray  fomefundameRtal error 
in  the  a  (Turned  data  :  for  the  degrees  of  heat  afligned 
by  Mr  Wedgwood  for  melting  gold,  filver,  and  cop 
per,  are  mere  than  quadruple  of  thofe  afllgned  by 
Bergman,  and  that  for  melting  iron  is  more  than  e- 
leven  times  greater ;  although  they  both  nearly  agree 
in  the  red  heat  of  iron,  which  Bergman  fays  to*  be 
1050  degrees, and  Wedgwood  1077.  ^-r  Magellan  is 
ofopinirn,  that  the  fault:  lies  in  Mortimer's  thermo 
meter,  which  Bergman  quotes  with  fome  diffidence 
(Sect.  197.  of  his  Sciagrapkia)  ;  and  thinks  it  probable, 
that  the  changes  caufed  by  heat,  on  this  metallic  ther 
mometer,  are  in  a  much  lefs  ir.creafmg  proportion  by 

intenfe 


C    185    ] 

back  again  to  their  former  ftate  by  the  addition  of 
the  phlogifton  they  had  loft  in  their  decompofitioa. 


intenfe  fire,  than  thofe  indicated  by  the  contradiction 
of  the  pure  clay,  happily  employed  by  Wedgwood  in 
his  thermometer.  He  therefore  added  another  column 
to  this  table,  marked  ffledgw.  with  the  degrees  of  the 
melting  heats  already  afcertained  by  this  lad  thermo 
meter,  as  being  the  neareft  to  truth. 

O    £>    !z!    W  H  t?  p  t-1 ,0  g  3  O 

§       r—*— i      <*-*-n  ~  ^"  ^ 

11. If.,  •."-.-    ? 

'      §        §         '•••.' 


00  CO  00     ^j      U»    O     O    b,t>    OO^OO'^    ^  C^    ?N  ^ 
^^^O       OOO-^ONO-j^^C^XP^  »S  "K 

0OU      ^       OOOo0-^OONW0^o"o  ^^ 


>-<  o  ^  b 


VO  v^  I 

•«^j    oo        -4^ 
--4   -J  O 


MO^      " 

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WKJCO  OOlWlHH^^^^JQ 

^4Ot>4  VDON'-JI-^-tJWUi^O 


00         £    I   3 
>-  ^-4  hn  t-r  •"{          «S>  -t    Oj 

fp' 

TV.  ^?.  By  faturating  phlogifton,  Profeflbr  Bergman 
means  to  exnrefs  the  nrnnottioaate  quantities  taken 


C     1 86     ] 

£ee  METALLURGY,  Part  I.  Seel,  i.  and  CHEMISTRY- 
Index  at  Metallic  Calces  and  Metals. 

All  the  metallic  fubftances  contain  phlogifton  ;  and 
when,  to  a  certain  degree,  deprived  of  it,  fall  into  a 
powder  like  an  earth  ;  but  their  attraftions  for  phlo- 
giikn  are  different. 

Moll  of  them,  when  melted  in  a  common  way,  and 
expcfed  to  the  air,  have  an  earthy  cruft  formed  upon 
the  furfac?,  which  cannot  again  be  reduced  tdhnetal 
without  the  addition  of  fome  inflammable  matter.  The 
bafe  metals  have  this  property. 

But  the  noble  metals,  viz.  platina,  gold,  and  diver, 
are  fo  firmly  united  to  the  phlogifton,  that  they  never 
calcine  under  fulion,  however  long  continued  ;  ard,  af 
ter  being  changed  into  a  calx  in  the  liquid  way,  when 
melted  in  the  fire,  they  reaiTume  their  metallic  form 
wiihout  any  other  phlogifloa  than  what  is  contained 
in  the  matter  cf  heat. 

Quickfilver  holds  a  kind  of  middle  place :  for,  like 
the  bafe  metals,  it  may  be  calcined,  though  not  rea 
dily  ;  and,  like  the  noble  ones,  it  may  be  reduced  by 
heat  alone. 

We  may  therefore  reckon  four  noble  or  perfect  me 
tals ;  viz.  gold,  platina,  filver,  anil  mercury;  becaufe, 
when  calcined,  they  recover  their  phlogifton  without 
the  addition  of  any  phlogiftic  fubftauce. 

But  as  tin,  lead,  copper,  and  iron,  cannot  be  redu 
ced  without  fiich  addition,  thefe  are  called  Ignoble  and 
iir.perficl  or  bafe  metals.  Kirivar?  s  Mineralogy. 

However, 


away  from  each  metallic  fubftance,  when  diiTolvcd  by 
means  of  acids,  and  of  courfe  reduced  to  a  calciform 
ftate.  The  laft  column  only  expreifes  their  attraction 
to  this  part  of  their  phlogifton,  not  to  that  which  ftill 
remains  united  to  them  in  a  calciform  ftate.  Withering. 


However,  all  thofe  eight  metals  (even  mercury, when 
folid)  are  malleable  to  a  confiderable  degree,  and  are 
called  entire  metals.  But 

Bifmuth,  zinc,  antimony,  arfenic,  cobalt,  nickel, 
manganefe,  molybdena,  and  wolfram,  are  fcarce  at  all 
malleable,  and  hence  they  are  called  femimetals.  Ne- 
verthelefs,  zinc  and  purified  nickel  are  more  malleable 
than  any  of  the  other  femimetals  ;  fo  that  we  have 
four  perfect  or  noble  metals,  four  imperfect  or  bafe, 
eight  entire,  and  nine  femimetals  (H). 

Order 


(H)  MrMongez  remarks,  that  the  following  are  the 
general  properties  of  metals,  when  confidered  as  phy- 
fical  bodies  ;  viz.  their  opacity,  great  fpecific  gravity, 
ductility,  tenacity,  cryftallization,  flavour,  and  even 
imell,  at  leaft  in  fome  of  them. 

It  is  from  their  denfity  that  their  gravity  and  opaci 
ty  proceed ;  this  Lift  being  fuch,  that,  even  reduced 
to  the  thinned  plates,  no  rays  of  light  can  pafs  through 
their  particles,  unlefs  there  remains  an  interftice  or 
pore  quite  free  from  the  metallic  fubftance.  Gold  leaf 
muft,  however,  be  excepted,  which  exhibits  a  fine  green 
by  tranfmitted  light. 

As  to  their  cryftallization,  it  has  been  found  to  take 
place  whenever  they  are  pure,  and  left  to  cool  very 
ilowly  by  themfelves,  after  having  been  perfectly  fufed. 
( See  Journal  de  Pbyftque  for  July  1 7  8 1 ,  p.  74 )  The 
favour  and  fmell  abovementioncd  are  very  perceptible 
in  the  reguline  fubftances  of  arfenic  and  antimony,  as 
well  as  in  lead,  copper,  and  iron. 

All  metals  are  conductors  of  electricity ;  and  more 
perfectly  fo  than  any  other  bodies  during  their  union 
with  plilogiften. 

They  are  foluble  either  in  nitrous  acid  and  in  de- 
phlogifHcated  marine  acid,  or  in  aqua-regia  ;  and  are 
preeipitable  in  fome  degree  by  cauflic  alkalies  ;  and  ex 
cept  platina  by  the  Pruflun  alkali. 

R  3  When 


C     188 


Order  I.     NOELE  or  PERFECT  METALS. 

I.  Gold ;  Aunim  fol  clymlcorum.  See  the  articles 
Gold;  alfb  CHEMISTKY-/;^' ;  and  METAL 
LURGY,  Part  II.  feel,  I. 


When  dephlogifticated,  they  communicate  a  tinge 
to  borax  and  to  microcofmic  fait,  or  at  leaft  render 
them  opaque. 

They  alfume  a  convex  furface  when  melted,  and  even 
a  globular  form,  if  in  a  fmall  quantity ;  and  though 
they  mix  for  the  moft  part  with  one  another  whilfl  in- 
fed,  yet  they  refufe  to  unite  with  unmetallic  fubftan- 
ces,even  their  own  calces,  iron  only  excepted,  which 
does  to  its  own  calx  {lightly  dephlogifticated  and  to 
plumbago.  Nickel  alfo,  and  fome  others,  may  contain 
i'ulphurin  their  leguline  ftate. 

Metals,  when  calcined,  are  capable  of  uniting  with 
other  calces  and  falts. 

Three  of  the  metallic  calces  have  been  found  to  be 
of  an  acid  nature  ;  nnz.  t;he  arfenical,  molybdenic,  and 
tungftenic  ;  from  which,  by  analogy,  the  nature  of  o- 
tlier  calces  may  be  conjectured. 

The  phlogifton  contained  in  metals  is  in  a  pure  Rate ;. 
viz.  without  water  and  aerial  acid,  with  which  it  is 
invariably  accompanied  in  all  other  compounds  except 
acid  airs  and  fu'phur. 

When  metallic  fubftances  are  naturally  found  in  the 
e-.mh  united  to  their  full  fliare  of  phlogifton,  and  confe- 
quently  pofTeiling  their  peculiar  properties,  they  are 
qalled  native. 

But  when  they  are  found  more  or  lefs  deprived  of 
their  phlogiflon  and  of  their  properties,  combined 
with  other -fubftances,  they  are  then  called  nilneralfiJ. 
is  the  mc.fl.  common  ftate  of  the.  mineral  king-, 


[     1 89     ] 

This  is  efteemed  the  principal  and  firO:  among  the 
metals ;  and  that  partly  lor  its  fcamty,  but  chiefly 
for  the  following  qualities : 

1 .  It  is  of  a  yellow  fhining  colour. 

2.  It  is  the  heavieft  of  all  known  !•  dies,  its  fpe- 
cilic  gravity  to  water  being  as  19,640  to  loco. 

3.  It  is  the  moft  tough  and  ductile  of  all  metals  ; 
becaufe  one  grain  of  it  may  be  ftretched  out  fo 
as  to  cover  a  lilver  wire  of  the  length  of  98  yards, 
by  which  means  T.S.TI7TT  of  a  grain  becomes  vi« 

4.  fible  to  the  naked  eye. 

Its  foftnefs  comes  neareft  to  that  of  lead,  and 
confequently  it  is  but  very  little  elaftic. 

5.  It  is  fixed  and  alterable  in  air  and  water,  and 
is  indeftruclibleby  the  common  action  of  fire. 

6.  When 


dom.  The  fubflance  fo  combined  with  them  is  called 
the  mlneraltjer^  and  the  whole  is  called  ore  ;  by  which 
name  are  alto  diftinguifhed  thefe  earths  and  ftones  in 
which  metallic  fubftances  are  contained. 

But  if  both  metallic  fubftances  are  mixed  together 
in  their  metallic  or  reguline  form,  without  the  lofs  of 
phlogifton,  they  are  then  faid  to  be  alloyed. 

When  the  mineralifer  is  of  a  faline  nature,  and  ren 
ders  the  metallic  combination  foluble  in  lefs  than 
20  times  its  weight  of  water,  the  compound  is  ranged 
among  falts.  Thus  the  vitriols  of  iron,  copper,  and 
zinc,  are  rather  claifed  with  falts  than  with  ores. 

The  moft  common  mineralifers  are,  fulphur,  arfenic, 
and  fixed  air  or  aerial  acid.  The  lead  common  are 
the  vitriolic  and  the  marine  acids.  The  phofphoric 
has  been  found  only  in  two  in  (lances  ;  •p/ss.  united  t§ 
lead,  difcovered  by  Gahn  ;  and  to  iron,  in  the  fiderite, 
as  Mr  Meyer  believes. 

Thofe  metallic  fubftances,  mineralifed  by  aerial  acid, 
a.r£  called  calclform  ores* 

M. 


[    190   j 

6.  When  melted,  it  reflects  a  bluifli-green  colour 
from  its  furface. 

7.  It  difTolves  in  aqua-regia,  in  the  dephlogifticated 
marine  acid,  and  alfo  (according  to  Crell  J)  in 
an  acid  obtained  by  diftilling  vitriolic  acid  from 
offmanganefe. 

8.  When  mixed  with  a  volatile  alkali  and  a  little 
of  the  acid  of  nitre,  by  means  of  precipitation 
out  of  aqua-regia,  it  burns  off  quickly,   in  t!».e 
leaft  degree  of  heat,  with  a  ftrong  fulmination. 

9.  It  is  diflblved,  fa  forma  Jictfl,  by  the  liver  of  ful- 
phur,  and  alfo  fomewliat  by  the  glafs  of  bifmuth(  i ). 

10.  It  is  not  carried  away  by  the  antimony  du 
ring  the    volatilifation  of  that   femi-metal,  and 


M.  Magellan  obferves,  that  if  the  new  doctrine  of 
the  French  chemifts,  who  afiert,  that  calces  of  metals 
are  a  compound  of  dephlogifticated  or  vital  air  with  the 
metallic  fubftance,  were  juft,  all  calciform  ores  ihould 
produce  this  vital  air  inftead  of  aerial  acid,  when  they 
are  reduced  to  their  metallic  form  ;  which  is  not  the 
cafe ;  neither  fhould  all  the  bafe  metals  and  femimetals 
absolutely  require  the  mixture  of  fome  phlogiftic  fub- 
ftance  in  order  to  their  being  reduced  from  the  Mate 
of  calces  to  their  metallic  form,  which  otherwife  would 
be  quite  ufelefs,  if  their  redu&icn  fimply  conufted  ia 
their  feparation  from  the  vital  or  dephlogifticated  air, 

(i)  Neither  fulphur  nor  fixed  alkali,  has  any  aft  ion 
on  gold ;  but  the  liver  of  fulphur,  which  is  a  com 
pound  of  both,  can  diliblve  it  in  the  dry  way  ;  fo  that 
if  a  proper  quantity  of  gold-leaves  be  put  in  a  cru 
cible  together  with  liver  of  fulphur,  afid  it  be  melted 
in  a  brifk  fire,  the  gold  is  thoroughly  dilfolvecl; 
and  if  the  whole  be  diluted  in  water,  the  gold  will 
be  kept  in  the  folution,  and  even  pafs  through  the  filtre 
along  with  it, 

(K) 


is  therefore  conveniently  feparated  from  other 
17 ictals  by  the  help  of  crude  antimony  ;  in  which 
procefs  the  other  metals  are  partly  made  volatile, 
•  and  fly  off  with  the  antimony,  and  partly  unite 
with  the  fulphur,  to  which  the  gold  has  no  at 
traction,  unlefs  by  means  of  ibme  uniting  body, 
or  by  along  digeftion  (K). 

11.  The  phofphorus  is  faid    to  have  ingrefs    into 
gold  (L). 

12.  If  mixed  with  a  lefs  portion  of  filver,  platina, 
copper,   iron,    and  zinc,    it    preferves  tolerably 
well  its  ducYilfty.     But, 

13.  When  mixed  with  tin,  it  becomes  very  brittle ; 
and  it  attracts  likewife  the  fmoke  of  that  metal, 
fo    as  to    be  fpoiled    if   melted    on    an    hearth 
where  tin  has  been  lately  melted  (M). 

14.  It 

(  K  )  Antimony  is  ufed  alfo  to  refine  gold  from  its 
alloy,  as  it  attenuates  and  carries  off  all  other  metallic 
fubftances  mixed  with  it,  without  excepting  the  filver ; 
whilft  lead  leaves  this  laft  behind,  and  even  adds  feme 
of  its  own  to  the  gold.  -PauBon,  p.  659. 

(L)  Gold,  reduced  into  thin  leaves,  is  not  acled 
upon  by  the  phoiphoric  acid  in  the  humid  way,  though 
the  fire  be  urged  till  luminous  decrepitations  take 
place  ;  but  when  it  paffes  that  point  which  feparates 
the  humid  from  the  dry  way,  Mr  Margraaf  obfer- 
ved  that  feme  purple  fcoria  were  formed,  which  is 
an  indication  that  this  concrete  acid  had  partly  cal 
cined  the  gold  during  its  fuiion.  Elements  de  Chymie 
tie  Dijon,  Vol.  III.  p.  131. 

Beiides  this,  a  drop  of  the  phofphoric  acid  on  the 
folution  of  gold  by  aqua-regia  precipitates  the  metal 
in  its  revived  ftate,  as  aflerted  by  the  academicians  of 
Dijon.  Magellan. 

(  M  )  The  fumes  of  a  fmgle  grain  of  tin  are  capable 
of  rendering  hard  eight  ounces  of  gold  ;  but  it  eafily 

reco- 


[       192       ] 

14.  It  requires  a  ftrong  beat  before  it  melts,  nearly 
as  much  or  a  little  more  than  copper. 

15.  It  mixes  or  amalgamates  readily  with  qiiick- 
filver.  See  METALLURGY,  Part  II.  feet.  I.  (N). 

1 6.  It  is  not  difiblved  by  the  glafs  of  lead,  and 
therefore  remains  on  the  cupel. 

A.  Native 


recovers  its  malleability  by  being  melted  on  the  fire* 
(Wallerius  and  Bomarees  Mineralogy.)  But  when  gold 
is  ^  mixed  with  arfenic,  cobalt,  nickel;  bifmnth,  or 
with  the  regulus  of  antimony,  it  only  lofes  great 
part  of  its  malleability ;  and  when  in  a  certain  pro 
portion,  it  may  be  calcined  and  vitrified  with  them. — 
(Falronl.) 

(N)  Bergman  doubts  if  ever  gold  has  been  found 
perfectly  pure  ;  and  Mr  Kir  wan  fays  that  it  is  very  fel- 
dom  found  fo,  being  generally  alloyed  with  filver, 
copper,  or  iron,  or  all  three.  As  to  the  gold  com 
monly  ufed  in  toys  and  other  objects  of  luxury,  eve 
ry  one  knows  that  it  is  purpofely  debafed  by  the  ar- 
tifts  with  copper  or  other  metals ;  and  of  late  it  has 
been  employed  in  various  pieces  of  jewellery,  to  form 
ornaftierits  of  various  colours  :  thus  a  great  alloy  of 
filver  (viz.  one-third  part),  gives  it  a  fhade  of  a  green 
colour  ;  a  fimilar  quantity  of  copper,  a  reddifli  one  ; 
a  mixture  of  arfenic,  or  filings  of  fteel,  in  the  pro 
portion  of  one-fourth  part,  gives  it  a  bluifh  caft  ;  fo 
that  having  the  yellow  naturally  in  the  pure  gold, 
and  the  white  in  pure  filver,  the  jewellers  have  al- 
xnoft  all  the  colours  to  diver fify  their  work.  Even 
in  the  currency  of  nvoney,  there  is  none  coined  out 
of  pure  gold,  which,  by  common  agreement,  is  cal 
led  gold  of  24  carats.  The  gold  coin  of  England, 
France,  and  Portugal,  only  contains  22  parts  of  pure 
gold,  and  two  of  alloy,  viz.  it  is  only  22  carats,  in 
the  common  faying;  that  of  Spain  is  but  of  2iT-| 

carats  t 


C    193    ] 

A.  Native  gold.  With  refpecl  to  the  figure  or  the 
quantity  in  which  gold  is  found  in  one  place,  it 
is  by  miners  divided  into, 

1.  Thin  fuperficial  plated  or  leaved  gold  ;  which 
con  flits  of  very  thin  plates  or  leaves,  like  paper. 

2.  Solid  or  maflive,   is  found  in  form  of  thick 
pieces. 

3.  Cryftallifed,  confifts  of  an  angular  figure. 

4.  Waih  gold,  or  gold   duft,  is  wafhed  out  of 
fands,  wherein  it  Les  in  form  of  loofe  grains 
and   lumps    (o).      See    other    diftinclions  of 
form  under  the  article  GOLD. 

J5.  Mineralifed  gold.  This  is  an  ore  in  which  the 
gold  is  fo  far  mineralifed,  or  fo  entangled  in  other 
bodies,  as  not  to  be  diflplved  by  the  aqu;a-regia. 

1.  Mineralifed   whh  fulphur  by  means  of  iron. 
Marcafitical  gold-ore  ;  Pyrites  aureus. 

2.  By    means    of   quickfilver.       It  is  found  in 
Hungary. 

3.  By  means  of  2mc  and  iron,  or  filver.     The 
Schemnitz  blende. 

See 


carats :  but  the  dncat  of  Holland  is  of  23|4  carats  ; 
and  the  zecchino  of  Venice,  of  i$\\  carats:  which 
lad  therefore,  it  would  feem,  is  the  purefl  gold  coin  of 
Europe.  (Paudon's  Metrologte.) 

(o)  M.  Daubenton,  in  his  Methodical  Tables  of 
Mineials,  enumerates  eight  forts  of  native  gold,  viz. 
i.  In  powder  ;  2.  In  grains  ;  3.  In  fmall  fpangles  ; 
4.  In  malles  or  lumps ;  5.  In  ftiaments  ;  6.  In  bran 
ches  like  vegetables;  7.  In  lamella;  and  8.  In  oclo- 
edral  cryflals. — He  obfervcs  alfo,  that  gold,  in  its 
reguline  (late,  is  formed,  either  i.  Into  angular  cry- 
ftals,  compofed  of  yellow  octoedres  ;  or,  2.  Into  irre 
gular  yellow  mafTes,  which,  being  broken,  ihow  a  gra~ 
nular  iiibftancs. 


[     '94     3 

See  otiier  varieties  of  mineralifed  gold  ores 
under  the  detached  article  GOLD,  'already  re 
ferred  to. 

IT.  Silver:  Argentum,  Luna.     See  the  article  SILVER. 
See  alfo  CHEMISTRY-//.'^;   and  METALLURGY, 
Part  II.  feel.  iii.  and  Part  III.  left.  iii. 
This  metal  is, 

a.  Of  a  vrhite  fliining  colour. 

b.  Its  fpecific  gravity  to  water  is,  according  to 
Cronfledt,  as   11,091   to    1000;  accordir.)-  to 
Bergman,  =  10,552  ;  and  according  to  Kir- 
wan,  11,095. 

c.  It  is  very  tough  or  du&ile,  'fo  that  a  grain  of 
it    may    be  frretchcd    rut    to  three    yards  in 
length  and  two  inches  in  breadth. 

d.  It  is  unalterable  in  air,  water,  and  fire. 

e.  It  diflblves  in  the  acid  cf  nitre,  and  alfo  by 
boiling  in  the  acid  of  vitriol. 

f.  If  precipitated  out  of  the  acid  nitre  with 
the  common  fait,  or  with  its  acid,  it  unites 
fo  ftrongly  with  this  laft  acid,  that  it  does  not 
part  from  it,  even  in  the  fire  itfelf,  but  melts 
with  it  into  a  rnafs  like  glafs,  which  is  called 
him  cornea  (p.) 


(p)  The  marine  acid  attracts  the  calx  of  filver,  but 
cannot  remove  its  phlogifton  ;  and  therefore  cannot 
diflblve  it  in  its  metallic  {late,  (Bergman.]  However, 
the  marine  acid,  if  well  concentrated,  or  rather  re- 
duTcdipto  an  aerial  form,  difiblves  filver  in  its  metal 
lic  flare,  (Fabronl.) 

Mr  Scheele,  and  after  him  Mr  Bertholet,  aflert  po- 
fltirely,  that  the  marine  acid,  being  dephlogiilicated 
by  its  diftiilation  over  manganefe  in  the  form  of  a  yel 
low  air  or  gas,  difiblves  all  the  metals,  without  excep- 

I  ting 


[.     195     1 

n.  It  does  not  unite  with  the  fcm'-metal  nickel 
during  the  fufion.  . 

b.  It  amalgamates  eafily  with  quickfilver. 

z\  It  is  in  the  dry  way  difTolved  by  the  liver  of 
fulphur. 

k.  It  has  a  ftrong  attraction  to  fulphur,  fo  as  rea 
dily  to  take  a  reddith  yellow  or  black  colour 
when  it  is  expofed  to  liver  vapours. 

/.  If  has  no  attraction  to  arfenic  ;  whence,  when 
the  red  arfenical  filver  ore,  or  ret/.^ultkn  ertz 
of  the  Germans,  is  put  into  the  fire,  the  arfe 
nic  flies  off,  and  leaves  the  fulphur  (which  in 
this  compound  was  the  medium  unutu,)  behind, 
united  with  the  filver  in  form  of  the  glafs  di 
ver  ore,  or  glafs  ertz. 

m.  It  is  not  diffolved  by  the  glafs  of  lead,  and 
consequently  it  remains  on  the  cupel. 

n.  It  is  exhaled  or  carried  off  by  volatile  metals 
and  acids ;  as  by  the  vapours  of  antimony, 
zinc,  and  the  ac'd  of  common  fait. 

o.  According  to  Cronftedt,  it  melts  more  eafily 
than  copper  ;  and  this  was  a  general  opink  »:. 
But  the  contrary,  as  Mr  Magellan  remarks, 
has  been  proved  by  means  of  the  nice  ther 
mometer  lately  invented  by  Wedgewood. — 
See  THERMOMETER.. 

Silver  is  found, 

A.  Native 


gold,  filver,  or  mercury.      See  Scheele's  Effay  5. 


The  vitriolic  acid  being  diRilled  alfo  over  tfre  man- 
,  diifolves  filver,  sjold,  and  mercury,  as  Dr  Crell 
illerts,  (Journal  de  PLyfiqne,  Oct.  1785,  p.  297.) 
Sliver  is  precipitated  from  the  vitriolic  and  nitrous 
-:.rine ;  and  from  the  nitrous,  in  great 
lie,    (Kir wan.) 
S 


st.  Native  or  pure  ;  which  mod  generally  is  nearly 
of  16  carats  ftandard  (CL). 

1.  Thin,  fuperficial,  plated  or  leaved. 

2.  Ip  form, 

a.  Of  fnaggs,  and  coarfe  fibres. 

b.  Of  fine  fibres.     Capillary  filver. 
r.  Arborefcent. 

cl.  Cryftalline  or  figured.     This  is  very  rare  : 

it  has  diftincl  fibres,  with  fhining  furfaces. 
JS.  Mixed  or  alloyed  with  other  metals. 

The  following  are  the  known  inftances  of  thefe 
mixtures  : 

1.  United  to  gold,  (Bergman's  Scingraphia,  §  154.) 

2.  Mixed  with  copper  ;  (Berg.  Sc.  §  155.) 

3.  United  to  gold  and  copper  ;  (Berg.  Sc.  §  156.) 

4.  Amalgamated   with    mercury,  found  in  the 
mines  of  Salberg  ;  (Fojler's  notes  to  Brunnich.) 

5.  United  to  iron  ;  (Berg.  Sc.  §  157.) 

6.  United  to  lead,  fometimes  in  fuch  quantities 
as  to  be  worth  the  expences  attending  the  fe- 
paration. 

7.  United  to  arfenic  ;  (Journal de  Phyjique,  1778, 
p.  50.) 

8.  United  to  antimony  ;  (Berg.  Sc.  §   159.) 

9.  Joined  to  the  regulus   of  arfenic  and  iron  ; 
(Berg.  Sc.  §   160.) 

10.  Mixed    with    the    alkaline    limeftone    from 
Annaberg,    defcribed    by  Mr    Jufti ;    (Brun- 
M.) 

1 1 .  Sandy  filver-ore,  without  pny  metallic  fhining. 

12.  Silver-ore  in  a  red-brown  fchillus,  defcribed 
by   Lehman :   it  is  ccmpofed  of  argillaceous 

earth, 


(qj  Wallerius  diftinguifhes  feven  fpecies  of  filver  : 
(fee  the  article  SILVER).  Dauhenton  reckons  eight 
varieties  of  nathe  wbifefiher,  arifing  from  their  pecu 
liar  forms. 


C    19?    ] 

earth,  micaceous  hematites,  fulphur,  calcarfc- 
ous  fpar,  fluor  mineralis,  lead,  and  filver. — 
It  contains  about  feven  or  eight  ounces  of  iil- 
ver  on  the  hundred  weight. 
1 3.  Soft  filvgr-ore.     It  is  found  among  the  marles 
and  argillaceous  earths  ;  and  is  of  various  co 
lours,  either  fmgly  or  mixed. 
C.  Diffblved  and  mineralifed. 
(i.)  With  fulphur  alone.      Glafs  filver  ore. 
This  is  duclile,    and  of  the  fame    colour  as 
lead  ;  tfl&  however,  becomes  blacker  in*the 
air.    It  has  therefore,  though  very  improper- 
ly,  got  the  name  of  glafs-ore  ;  for  that  name 
rather  belongs  to  the  mlnera  argcn'i  cornea* 
or  horn  filver  ore,  if  indeed  any  filver  ore 
can  be  confidered  as  glafly. 
It  is  found, 

1.  In  crufts,  plates,  or  leaves. 

2.  Grown  into 

ft.  Snaggs,  and 

b.  Cryitalline  figures. 

It  is  generally  either  of  a  lamellar  or  a 

grained  texture. 

The  glafs  filver  ore  is  the  richeft  of  all   filver 

ores ;    fmce    the   fulphur,    which  is  united 

with  the  filver  in  this  ore,  makes  but  a  very 

fmall  quantity  of  its  weight 

(2.)     Arfenico-martial    filver    ore,    Wall  ertz, 

Germ.) 

This  ore  contains  illvcr  and  iron  mineralifed 
by  arfenic  ;  the  arfenic  in  a  larger  propor 
tion  than  the  iron.  This  is  the  Pyrites  ar- 
gentcus  of  Henckel. 

1.  It  is  a  hard  fubftance,  of  a  white  (liming 
appearance,  and  of  a  compact,  lamellar,  or 
fibrous  texture.      (Kiriuan,  fp.  7.) 

2.  Of  a  yellowiih  white  colour,  and  of  a  (Iri- 
a:?d    ftruflure,    refembling    bifmuth,    but 

S  2  much 


r     i9s    ] 

much    harder.      [Kirwan,    fp.    3.)— It    is 
found  near  Guadanal  canal  in  Spain. 

3.  Near  the  fame  place  is  found  alfo  another 
ore  of  the  fame  kind,  which  is  very  ibft  and 
eafily  cut  ;  and  when  cut,  has  a  brilliant 
metallic  appearance.  It  confifts  of  con- 
choidal  laminae.  The  quintal  contains  only 
from  four  to  fix  ounces  of  filver ;  but  it  is 
eafily  reduced  by  evaporating  the  arfenic, 
which  then  leaves  the  fifrer  flightly  conta 
minated  with  iron.  (KJfrwan,  fp.  4.) 
(3.)  With  fulphur  and  arfenic.  The  red  or 
ruby-like  filver  ore.  The  rotbguldcn  of  the 
Germans. 

The  colour  of  this  ore  varies  as  the  propor 
tion  of  the  ingredients  varies  in  the  mix 
ture,  viz.  from  dark  grey  to  deep  red ;  but 
xvhen  it  is  rubbed  or  pounded,  it  always 
gives  a  red  colour. 

a.  Grey  arfenical  filver  ore. 

1.  Plated,  crufted,  or  leaved. 

2.  Solid. 

b.  The  red  arfenical  filver  ere  : 

1.  Plated  crufted,  or  leaved  ; 

2.  Solid  or  fcaly. 

3.  Cryftallifed(R.) 

In 


(R)  Wallerius  mentions  the  fix  following  varieties 
of  this  notable  ore  in  his  Species  388,  viz.  i.  The  red 
opaque,  like  cinnabar,  from  Andreafberg  in  the  Hartz, 
and  from  Salberg  in  Weflmannia :  2.  The  bluifli,  from 
Freiberg  and  Annaberg  :  3.  The  grey,  from  Freiberg 
and  Andreafberg  :  4.  The  red  tranfparent  amorphous, 
of  the  garnet  colour,  from  Potcfi  and  loachimu1  al : 
5.  The  red  tranfparent,  cryftallifed  into  prifmatic  de- 
caedres,  or  dodecaedres,  from  Hungary,  Alface,  and 

the 


[     199     J 

In  this  laft  form  it  Ihows  the  moft  beati- 
tiiul  red  colour,  and  is  often  femi- 
tranfparent.  It  contains  about  60  p:r 
cent,  in  filver. 

(4.)  With  fulphur,  little  arfenic,  and  iron. — 
Schwartz,  ertz  Schwartz  gu/dtrt,  Silber  muun. 
Germ.) 

This  is  a  friable,  weathered,  decayed  ore. 
a.  Of  a  black  or  footy  colour  ;  and  is  there 
fore  called  by  the  Germans J^tterfekwartz,, 
or  ru/Jjgtes-enz,. 
(5*)  With  fulphurated  arfeni:  and  copper.    The 

tv  ij^dden  of  the   Germans. 
This,  in  its  folid  form,  is  of  a  light  grey  co 
lour,  and   of  a   dull  and  fteel-grained    tex 
ture.      Its  proportion  of  filver  is  from  10  to 
^O  per  cent. 

(6)   With  fulphurated   arfenic   and   iron.      The 
tvsifertz,  or  while  filver  ore  of  the  Germans. 
This   is  an  arfenical  pyrites,    which  contains 
Silver;  it  occurs  in  the  iaxon  mines,  and  fo 
exactly  refembles  the  common  arfeuical  py 
rites,  as  not  t)  be  diftinguifhed  from  it.  by 
fight  alone,  or  without  other  means. 
(7.)  With  fulphurated  antimony. 

a.  Of  a  dark  grey  and  fomewhat  brownifn  co 
lour  ;  the  labcrel-z,  of  the  Germans. 
I.  Of  a  blackifh  blue  colour. 

i.  In  form  of  capillary  cryftals.     FqdereriZy 

or  plumofe  filver  ore. 
(8.)  With  iron,  arfenic,  and  cobalt,  inineralifed 

by  fulphur. 

This  ore  looks  like  the   fiu?:ij~^.!.!in    defcribcd 

above ;  but  is  diftinguifhed  by  the  rofe  co- 

S  3  loured 


the  Duchy  of  Deux  Fonts  :   6.  The  only  fuperficially 
red  ore,  from  Salberg  and  EhrenfriederichRlorf. 


[       200       ] 

loured  particles  of  cobalt,  difperfed  through 
dark  brown,  blackifh,  or  grey,  and  fometimes 
fhining  folid  mafs.     It  is  to  this  fpecies  of 
ores  that  the  filver  goofe  dung  ore  belongs. 
(9.)  With  fulphtirated  copper  and  antimony. — 

The  Dn\fat>-Iertiz. 

This  refembles  both  in  colour  and  texture  the 
dark-coloured  weiffgialden.  When  rubbed,  it 
gives  a  red  powder. 

a.  Solid. 

b.  Cryftallifed. 

(10.)  With  fulphurated  zinc.     The  pechllsndc  of 

the  Germans. 
This  is  a  zinc    ore,    mock    lead,    or  blende, 

which  contains  filver,  and  is  found  among 

rich  filver  and  gold  ores. 
a.  Of  a  metallic  changeable  colour. 

1.  Solid  and  with  fine  fcales. 

2.  In  form  of  balls.  The  kugel-erte,  or  ball  ore. 
I,    Black  mock    lead,    ©r    blende,    found  in 

Saxony.     This  is  alfo  found, 

1.  Solid,  and  with  fine  fcales  ; 

2.  And  in  form  of  balls. 

(  1 1. )  With  fulphurated  lead;  potters  ore.      Ga~ 

Una  ;  lleyglanz,. 

(12.)  With  fulphurated  lead  and  antimony,  call 
ed  Jtiiperz. 
(  i 3- )  With  fulphurated  iron.     Silberhalitgier  lues  ; 

marcafite  holding  filver. 

(14.)  With  fulphurated  and    arfenical    cobalt; 
dentil  fces  being  fometimes  found  in  the  (tone. 
Thefe  kinds  keep  well  in  water ;  but  general 
ly  wither  in  the  air,  and  lofe  the  filver  they 
contain. 

(15.)   Mineralifed  by  fulphur,  with  regulus    of 
antimony  and  barytes.  The  butter-milk  ore., 
This  is  found  in  the  form  of  thin  particles,  oa 
granular  fpar,  (Kirwan,  fp.  13.) 

(16.  Coir* 


[       201        ] 

(16.)  Combuftible  filver  ore. 

This   is    a    black  and  brittle    fubftance,    and 

leaves  about  6  per  cent,  of  filver  in  its  afhes. 

It  is  in  fact  a  coal  in  which  filver  is  found. 

(Kir<wan,  fp.  14.) 

(17.)  With  the  acid  of  common  fait.     Minera 

argenti  cornea.     Hornefz,  or  horn-filver  ore. 
This  is  the  fcarceft  fdver  ore  ;  it  is  of  a  white 
or  pearl  colour,  changeable  or  varying  on 
the  Aiiface,  femi-tranfparent,  and  fomewhat 
ductile  both  v\hen  crude  and  when  melted. 
It  cannot  be  decompofed  without  forne  ad 
mixture  offuch  fabllances  as  attract  the  acid 
offea.falt. 
III.  Platina  del  Pinto ;  Juan  blanca* 

This  metal  is  a  recent  difcovery  of  our  times ;  and 
is  defcribed  with  great  accuracy  by  Scheffer,  in 
the  Acts  of  the  Royal  Academy  of  Sciences  at 
Stockholm  for  the  year  1752;  as  alfo  by  Dr 
Lewis,  in  the  Philosophical  Tranfaclions  for  the 
year  1754*  vol.  xlviii.  and  by  many  other  wri 
ters.  By  thefe  defcriptions  we  are  convinced  of 
the  refemblance  this  metal  bears  to  gold ;  ancl 
therefore  wemuft  allow  it  to  be  called  white  gold. 
It  has,  however,  a  variety  of  diftinguiiliing  qua 
lities  befides  its  colour,  which  afcertain  its  pecu. 
liar  nature  :  All  which,  with  its  hiflory,  ufes, 
Sec.  are  particularly  defcribed  under  the  detached 
article  PLATINA.  See  alfo  CHEMISTRY-//^*  ;  and 
METALLURGY,  Part  II.  Sect,  ii. 

1.  It  is  of  a  white  colour. 

2.  It  is  fo  refractory  in  the  fire,  that  there  is  no 
degree  of  heat  yet  found  by  which  it  can  be 
brought  into  fufion  by  itfelf,  the  burning- 
glafs    excepted.      But,    when    mixed    with 
other  metals  and  femimetals,  it  melts  very 
eafily,  and  efpecially  with  arfcnic,  both  in 
its.  metallic  form  and  in  form  ofa  calx  orglafs. 

IV, 


[       202       ] 

JV.  Quickfilver,  mercury.  Hydrargyrum^  Argentum  vi- 
<vum>  Mercurius.  See  the  article  QUICKSILVER; 
CHEMISTRY-/WW,  at  Mercury  ;  and  METALLUR 
GY,  Part  II.  feet,  vlii. 

Mercury  diftinguifhes  itfelf  from  all  metals  by  the 
following  qualities  (s.) 
a.  Its  colour  is  white  and  fhining,   little  darker 

than  that  of  filver. 
I.  It  is  fluid  in  the  cold,  and  divifible  by  the  lead 

force  ;  but,  as  it  only  (licks  to  a  few  bodies  to 

which  it  has   an   attraction,  it  is  faid  that  it 

does  not  wet. 
c.  It  is  volatile  in  the  fire. 

d.  It 


(s)  It  were  almoft  fuperfluous,  fays  Mr  Kirwan,  to 
mention  any  other  character  of  quickfilver  than  its  li 
quidity,  to  diftinguifh  it  from  other  metals.  In  re 
gard  to  this  property,  Bergman  obferves,  that  mer 
cury  constitutes  one  extreme  among  the  metals,  and 
platina  the  other  ;  fmce  it  requires  to  be  melted  only 
in  fuch  a  degree  of  heat  as  is  rarely  wanting  in  our  at- 
mofphere,  and  boils  at  the  600  degrees  nearly  after 
lead  melts.  See  the  table  at  p.  in.  Note.  But  when 
the  cold  is  increafed  to  the  temperature  denoted  by  40 
degrees  below  both  of  Fahrenheit's  and  of  the  Swediih 
thermometer,  which  both  coincide  in  that  point  (fmce 
212 — 32,  or  180  :  100  : :  32+40,  cr  72  :  40),  this 
metal  concretes  like  any  ether  metal,  and  becomes 
quite  folid  ;  (fee  Philofophical  Tranfactions  for  1783, 
p.  303.)  Mercury  in  its  common  (late,  therefore, 
according  to  Bergman  (Treatife  cf  Ele<3,  Attract,  j,  is 
to  be  confidered  as  a  meul  in  fufion ;  and  fmce  in  its 
{olid  (late  it  is  nearly  as  malleable  as  lead,  it  by  no 
means  ought  to  be  placed  among  the  femimetals, 
btherwife  every  other  entire  metal  fhould  be  confide 
red' as  brittle,  for  none  is  malleable  when  in  fufion. 


C    203    J 

(1.  It  attraJb  the  other  femimetals  and  metals  : 
and  unites  with  them  all  except  cobalt  and  nic 
kel,  with  which  it  cannot  by  any  means  yet 
known  be  made  to  mix.  This  union  is  called 
amalgamation.  This  amalgamation,  or  mix- 
tion  of  metallic  bodies,  according  to  the  rea- 
dinefs  with  which  they  unite  or  mix,  is  in  the 
following  progreilion,  vi:s.  gold,  filvcr,  lead, 
tin,  zinc,  bifmuth,  copper,  iron,  and  the  rc- 
guhis  of  antimony ;  the  three  latter,  how 
ever,  do  not  very  readily  amalgamate.  The 
iron  requires  a  folution  of  the  vitriol  of  iron, 
as  a  medium  to  promote  the  union. 

f.  It  diilblves  in  fpirit  of  nitre,  out  of  which  it  is 
precipitated  by  a  volatile  alkali,  (T)  and  com 
mon 


(T)  i.  Mercury  is  diiTolved  with  great  rapidity  by 
nitrous  acid :  the  liquor  is  of  a  greenifh  blue  colour, 
but  afterwards  lofes  it  and  becomes  limpid.  This  fo 
lution,  when  made  without  heat,  is  ufed  as  a  teft 
for  the  analyfis  of  mineral  waters,  and  has  different 
properties  from  that  made  with  the  help  of  he.it.  In 
the  firft  cafe,  fays  Bergman,  very  little  phlogiilon  is 
loft,  and  the  fait  eafily  cryftallifes,  being  white  and 
fcarcely  acrid.  It  is  not  precipitated  by  diftilled  wa 
ter  ;  but  by  cauftic  vegetable  alkali,  it  is  precipitated 
of  a  yellowifh  colour  ;  by  mild  alkali,  the  precipita 
tion  is  white  ;  by  mineral  alkali,  it  is  yellow,  but  it 
foon  grows  alfo  white  ;  by  volatile  alkali,  it  turns  to  a 
greyifh-black  colour  ;  by  Glauber's  fait  or  by  pure  vi 
triolic  acid,  the  precipitation  is  white,  granulated,  and 
in  a  fmall  quantity  ;  nor,  if  this  precipitant  has  been 
fparingly  ufed,  does  this  colour  appear  in  lefs  than  an 
hour  ;  by  muriatic  acid,  or  common  fait,  the  pre 
cipitation  is  alfo  white,  but  in  a  Urge  quantity,  and  in 
curdles. 

2.  But 


[     204     ] 

mon  fait,  in  form  of  a  white  powder  ;  but  if 
<i  fixed  alkali  is  ufed,  a  yellow  powder  or  calx 
is  obtained 


2.  But  if  the  mercurial  folution  be  put  over  a  fand- 
hcat,  it  may  be  charged  with  a  quantity  of  mercury 
equal  almoft  to  its  weight.  Ac-cording  to  the  chemiils 
of  Dijon,  10  ounces  of  nitrous  acid  may  diflblve  eight 
of  mercury.  The  action  of  the  folvent  becomes  ftronger 
with  the  heat ;  emits  great  quantity  of  vapours ;  und 
if  not  taken  from  the  fire,  will  be  too  far  evaporated. 
Difiilled  water  will  precipitate  from  this  fulution  a 
Avhite  calx,  becaufe  it  is  more  dephlogillicated,  and 
t:he  folvent  is  overcharged  with  it ;  and  the  water 
changing  the  denfity  of  the  liquor,  diminilhes  the 
adheiion  of  the  calx,  as  Fonrcroy  remarks.  This 
white  calx  w'll  turn  yellow,  if  boiling  water  be  pour 
ed  on  it.  The  vegetable  alkali  precipitates  it  of  a 
brownilli  yellow,  which  by  degrees  afTumes  a  pale 
yellow  tinge:  the  mild  vegetable,  and  the  mineral  al 
kalies,  produce  nearly  the  fame  colour ;  though  when 
this  laft  is  employed,  the  colour  turns  afterwards  to 
white.  The  precipitation  by  volatile  alkali  is  quite 
white  alfo  ;  that  by  the  vitriolic  acid  is  yellow  ;  and 
finally,  a  copious,  white  mucilaginous  matter  is  the 
precipitate  by  the  marine  acid. 

$.  This  folution  by  nitrous  acid  is  very  cauft'c  ; 
corrodes  and  deftroys  animal  fubftances ;  when  it 
falls  on  the  (kin,  ftains  it  of  a  deep  purple  brown  co. 
Icur,  which  appears  black  :  the  ftains  do  not  go  oiF 
Before  die  fepar.uicn  of  the  epidermis,  which  Kills  a- 
way  in  fcales  or  a  kind  of  fears.  It  is  ufed  in  furgery  as 
a  powerful  efcharotic,  and  is  called  mercurial  <wctlcr. 

4.  The  fame  folution,  by  cooling,  is  fufceptible  of 
forming  cryftals,  which  vary  from  one  another  ac 
cording  to  circumftances  :  for  the  moil  part  they  are 
like  needles  ;  are  very  cauftic ;  redden  the  {kin  ;  av-.l 

detonate 


C    205    ] 

/.   But  it  requires  a  boiling  heat  to  diffolve  it  in 

oil  of  vitriol  (u). 
g.  It  is  not  affected  by  the  acid  of  common  fait, 

unlefs  it  be  previoully  di  delved  by  other  acids 


detonate  when  put  on  burning  coals,  provided  they  be 
dry.  They  are  called  mercurial  nitre,  which  fufes  when 
heated  in  a  crucible  ;  exhales  reddifn  fumes  ;  afiumes  a 
deep  yellow  colour,  which  afterwards  turns  to  orange, 
and  at  laft  to  a  brilliant  red  :  in  this  ftate  it  is  called 
rtd precipitate,  or  arcanum  coraliinum.  It  mufl:  be  made 
in  a  rrmtrafs  with  a  gentle  heat  if  it  is  defigned  to  be 
corrofive  for  chirurgical  purpofes. 

(u)  i.  The  vitriolic  acid,  concentrated  and  boiling 
hot,  feizes  on  mercury,  and  prefently  reduces  it  if  ur 
ged  by  heat  to  a  kind  of  white  powder,  which  turns 
yellow  by  the  afTufion  of  hot  water,  but  does  not  dif- 
iblve  in  it :  this  is  called  turlith  mineral :  but  if  cold 
water,  inftead  of  hot,  was  poured  in  the  white  rnafs, 
the  powder  would  not  change  its  wlute  colour  into  yel 
low  as  was  faid  above  about  the  nitrous  folution. 

2.  If  Mercury  be  rarefied  by  heat  into  vapours,  nnd 
theie  meet  with  thofe  fomarine  acid  in  the  fame  ftate, 
corrofive  fublimate  at  will  be  formed.     This  metallic 
fait  fhoots  into  cryftals  pointed  like  daggers,  which  are 
the  ftrongeft  of  all  poifons.     But  there  are  various  o- 
ther  procefies  found  in  chemical  authors  to  make  this 
fait  with  more  or  kfs   trouble.     See  CHEMISTRY,  n° 
814 — 8  [8. 

3.  If  corrofive  fublimate  be  mixed  with  tin  and  di- 
ftilled,  a  very  fmoking  liquor   is  produced,  called  by 
the  name  of  its  inventor  the  footing  licitor  r.f  Libavius. 
See  CHEMISTRY,  n°  oic. 

The  muriatic  acid  in  the  fublimate  is  net  faturated, 
and  from  hence  proceeds  its  great  corrofive  power  ;  for 
if  afrefii  quantity  of  mercury  be  added  to  L,  and  fub- 
iimed  a  fecond  or  third  lime,  a  fweet,  or  mixed  fub 
limate 


[       206       ] 

(v)  ;  in  which  cafe  only  they  both  unite  with 
one  another,  and  may  be  fublimed  together  ; 
this  fublimate  is  a  Mrong  poifon. 
It  unites  with  fulphur  by  grinding  ;  and  then 
produces  a  black  powder  called  atbiops  mincra- 
lis  (w),  which  fublimes  into  a  red  ftriated  body 
cinnabar. 


limate,  called  m.rcurius  dulcis,  is  produced,  which  is 
not  poifcnous,  and  is  given  internally  as  a  purgative, 
or  anemetic,  according  to  the  dofe.  See  CHEMISTRY, 
n°8i9. 

(v)  Muriatic  acid  does  not  act  upon  quickfilver  un- 
lefs  this  lait  be  previoufly  deprived  of  as  much  phlogi- 
fton,  as  TTO^O  of  the  quantity  contained  in  the  hundred 
of  filver,  or  of  TyT  in  the  hundred  of  zinc.  (See  Berg 
man's  Sciagraphia,  and  his  treatife  De  Phlogijti  qvami- 
tatc.) 

(w)  The  academicians  of  Dijon  fay,  that  the  true 
proportion  to  make  this  sethiops,  is  that  of  one  part 
of  brimftone  witlrfour  of  mercury.  Fourcroy  directs 
cnly  one  of  mercury,  with  three  of  flowers  of  fulphur, 
to  be  triturated,  till  the  mercury  is  extinguished.  A 
black  powder  is  then  produced,  which  is  the  sethiops 
mineral.  The  combination  is  better  effected  when  the 
mercury  is  mixed  with  die  fufed  fiilphur  :  by  agita 
ting  this  mixture,  it  becomes  black,  and  eafily  takes 
fire  ;  it  fhould  be  then^token  from  the  fire,  and  the 
flame  fhould  be  extinguished  a  little  after,  Mining  the 
xnafs  till  it  becomes  into  folid  clots.  If  this  fubftance 
be  expofed  to  a  great  degree  of  heat,  it  takes  fire,  the 
fulphur  is  confumed,  and  a  fubftance  remains  which  is 
of  a  violet  colour  when  pulverifed.  This  powder  be 
ing  put  into  malraiies,  till  their  bottoms  become  red 
by  the  force  of  fire,  is  fublimed  after  fome  hours,  and 
artificial  cinnabar  is  found  in  the  top  of  the  veiiels  cry- 
ftallifed  into  brown  red  needles. 

2  Mercury 


I  207  ] 

i*  Thefulphur  is  again  feparated  from  the  quick- 
filver,  by  adding  iron  or  lime,  to  which  the  ful- 
phur  attaches  itfelf,  leaving  the  quickfilver  to 
be  diftilled  over  in  a  metallic  form  ;  but  if  a 
fixed  alkali  be  ufed,  fome  part  of  the  quickfil 
ver  will  remain  diiT©l  ved  in  the  refiduum,  which 
is  a  liver  of  fulphur. 

Quickfilver  is  found, 

A.  Native,  or  in  a  metallic  flate.     Msrcunus  nati- 

wist  or  virgineus. 

This  is  found  in  the  quickfilver  mines  at  Idra  in 
Friuli,  or  the  Lower  Austria,  in  clay,  or  in  a 
black  flaty  lapis  ollaris,  out  of  which  it  runs, 
either  fpontaneoufly,  or  by  being  warmed  even 
in  the  hands. 

B.  United  to  gold  or  filver.     Hydrargyrum  argents 

vel  aitro  adunatum. 

Mr  Kirwan  aflerts,  on  the  authorities  of  Monet 
and  Lin,  Von  Gmelin,  that  in  Sweden  and 
Germany  mercury  has  been  found  united  to 
filver  in  the  form  of  a  fomewhat  hard  and  brit 
tle  amalgam. 

Rome  de  1'Ifle  had  a  fpecimen  of  this  natural 
amalgam  from  Germany,  which  is  imbedded 
in  a  quartzofe  mafs,  and  mixed  with  cinnabar, 
as  Mr  Mongez  afferts  ;  and  he  adds,  that  in 
the  royal  cabinet,  at  the  king's  garden  at  Pa 
ris,  is  depofited  another  fine  fpecimen  of  this 
mercurial  ore,  which  was  found  cryftallifed  in 
the  mine  called  Carolina  at  Muchel-lanfberg  in 
T  the 


Mercury,  divided  by  means  of  a  rapid  and  continu 
al  motion,  as  that  of  a  mill-wheel,  gradually  change* 
itfelf  into  a  very  fine  black  powder,  which  is  called 
athiops  per  fe,  on  account  of  its  colour,  in  order  to  di« 
ftinguifli  it  from  this  athiofs  mineml'u  mentioned  in  the 
text. 


[    208    ] 

the  duchy  of  Deux  Fonts.  M.  de  Plfle  fpeaks 
alfo  very  politively  of  a  fpecimen  of  native 
gold  from  Hungary,  which  feems  to  be  a  na 
tural  amalgam  of  gold  and  mercury.  It  is 
compofed  of  quadrangular  prifms,  of  a  grey- 
idi  yellow  colour,  and  of  a  brittle  texture. 
This  fpecimen  is  alfo  in  the  king's  cabinet  at 
the  royal  garden  at  Paris. 

Mr  Kirwan,  fpeaking  of  the  method  of  examin 
ing  the  purity  of  gold  by  the  moid  way,  fup- 
pofes,  with  Sir  Torbern  Bergman,  that  there 
are  natural  amalgamations  cf  mercury  with 
gold  and  filver  :  and  Neumann  obferves,  that 
ibmetimes  a  mineral,  containing  gold  or  fil- 
ver,  is  met  with  among  mercurial  ores,  al 
though  this  is  a  ejreat  rarity. 

It  is  evident,  therefore,  that  there  naturally  ex- 
ifl  various  ores  of  quickfilver,  amalgamated 
with  filver,  gold,  and  other  minerals,  although 
they  be  butfeldom  met  with. 
C.  Mineralifed, 

[i.]  Withfulphur. 

A.  Pure  cinnabar,  Ctnnataris  nattva. 

a.  Loofe  or  friable  cinnabar  like  red  ochre. 
I.  Indurated  or  folid  cinnabar.     It  is  of  a 

deep  red  colour  ;  and,  with  refpecl  to  its 

texture,  is  either, 

1.  Steel-grained; 

2.  Radiated ; 

3.  Compofed  of  fmall  cubes,  or  fcaly ;  or 

4.  Cryftallifed,  in  a  cubical  form  ;  it  is 
tranfparent,  and  deep  red  like  a  ruby. 

B.  Impure  cinnabars. 

(i.)  A  mercurial  ore  is  found  in  Idria, 
fays  Gellert,  where  the  mercury  lies  in  an 
earth  or  (lone,  as  if  it  were  in  a  dead  form  ; 
and  has  the  appearance  of  a  red-brown  iron- 
flone ;  but  it  is  much  heavier  than  that.  It 

contains 


C 

contains  from  three  quarters  to  feven  eighths 
of  the  pureft  mercury  ;  leaves,  after  diftilla- 
tion,  a  very  black  ftrong  earth  behind  ;  and 
gives  fome  marks  of  cinnabar. 

2.)  Liver  ore,  which  is  moft  common  in 
Idria,  and  has  its  name  from  its  colour.—- 
Outwardly  it  refembles  an  indurated  iron- 
clay  ;  but  its  weight  difcovers  that  its  con 
tents  are  metallic.  It  yields  fornetimes  80 
pounds  of  quickfilver  per  hundred  weight. 

3.  Burning  ore;    brand-trz    in  German. 
This  ore  may  be  lighted  at  the  candle  ;  and 
yields  from  nine  to  50  pounds  of  quicklilver 
per  hundred  weight.     Brunnlcb. 
[[2.3  With  iron  by  fulphur.     Pyritous  cinnabar. 
Sir  Torbern  Bergman  "mferted  this  ore  in  the 
1 77th  fe&ion  of  his  Sciagraph  iat  and  feems  doubt 
ful  whether  this  be  a  diftincl  fpecies  from  the 
cinnabar  ;  as  the  iron  is  perhaps,  fays  he,  on 
ly  mechanically  diffufed  therein.     Mr  Mongcz 
remarks,  that  there  are  but  a  few  inftances  of 
cinnabar  in  which  iron  is  not  found  in  its  cal 
cined  form  ;  though,  in  the  act  of  the  ore  be 
ing  reduced,  it  paifes  to  its  metallic  ftate,  and 
becomes  capable  of  being  acted  en  by  theload- 
llone. 

Another  pyritotis  ore  of  cinnabar  was  found 
at  Menidot,  near  St  Lo  in  Lower  Normandy. 
It  confided  in  grains  of  different  fizes,  of  a 
red  brown  colour:  they  had  a  vitriolic  tafte 
and  fulphureous  fmell.  Found  alfo  at  Al- 
maden  in  Spain,  and  at  Stahlberg  in  the  Pa 
latinate  ,  though  at  this  laft  place  they  are  of 
a  dodecaedral  form. 

£3-]  With  filver    by  the    aerial  acid,    and  ful 
phur. 

This  feems  to  be  a  native  precipitate  per  /£, 

or  calx  of  mercury.     It  is  faid  to  have  been 

T  2  lately 


[    210    ] 

lately  found  in  Idria,  in  hard  compact  mallei 
of  a  brownifh-red  colour  ;  fee  Journal  de  Pky~ 
Jtguefcr  Jar  nary  1784,  p.  6l.      If  this  account 
can  be  relied  upon,  it  will  prove,  that  quick- 
filver,  even  in  a  calciform   itate  is  naturally 
found  mineralifed  with  filver  by  means  of  ful- 
phur. 
£4.]  With  fulphur  and  copper. 

This  ore  is  blackifli  grey,  of  a  glaffy  texture, 
and  brittle ;  crackles  and  fplits  exccflively  in 
the  fife  \  and  when  the  quickfilver  and  fulphur 
are  evaporated,  the  copper  is  difcovered  by  its 
common  opaque  red  colour  in  the  glafs  t>f  bo 
rax,  which,  when  farther  forced  in  the  fire, 
or  dilutedj  becomes  green  and  tranfparenf.  It 
is  found  at  Mufchlanfberg  in  the  duchy  of 
Deux  Fonts. 

[5.]  Mincralt&d  by    the   nwine    and  vitriolic 
acids. 

Mineralogy  owes  the  difcovery  of  this  ore  to 
Mr  Woulfe,  who  publifhed  an  account  of  it 
in  the  Philofophical  Tranfaftions  for  1776. 
It  was  found  in  the  duchy  of  Deux  Fonts,  at 
the  mine  diftinguifhed  by  the  name  of  Obertnof- 
chal  It  had  a  fpar-like  appearance.  This  ore 
is  either  bright  and  white,  or  yellow  or  black. 
It  was  mixed  with  cinnabar  in  a  {tony  matrix  ; 
and  being  well  mixed  with  one-third  of  its 
weight  of  vegetable  alkali,  afforded  cubic  and 
oclagonal  cryilals  ;  that  is,  fait  of  Sylvius  and 
vitriolated  tartar. 

The  marine  fait  of  this  mercury  is  in  the 
(late  of  fublimate  corrofive. 

Order  II.     IMPERFECT  or  BASE  METALS. 

Tin.  Stannum  ;  Jupiter.  (See  the  detached  article 
TIN:  Alfo  CHEMISTRY-//^*;  and  METALLURGY, 
Part  II.  fetf.  vi,  and  Part  IIL-fed.  vi.) 

This 


C    213    ] 

2.  In  the  form  of  cryftalline  metallic  laminse,  or 
laminated  cryftals,  rifmg  fide  by  fide  out  of  an 
edging,  which  fhone    like  melted  tin :    they 
were  almoft  as  thin  'as  flakes  or  fcales  of  talc, 
interfering  each  other  in    various  directions, 
with  fome  cavities  between  them,  within  which 
appeared  many  fpecks  and  granules  of  tin,  that 
could  be  eafily  cut  with  a  knife  :  this  was  alfo 
found  in  Cornwall. 

3.  In  a  mafTy  form,  more  than  one  inch  thick 
in  fome  places,  and  inclofed  in  a  kind  of  quart- 
zous  ftone  ;  or  rather  in  an  hard  cruft  of  cry- 
ftallifed  arfenic. 

(2.)  Calciform  Ores  of  Tin. 

A.  In  form  of  a  calx,  Stanntim  cakiforme. 
A.   Indurated,  or  vitrified. 

i.  Mixed  with  a  fmall  portion  of  the  calx  of 
arfenic. 

a.  Solid  tin  ore,  without  any  determinate 
figure.     Tin-ftone. 

It  refembles  a  garnet  of  a  blackifh 
brown  colour,  but  is  much  heavier  ;  and 
has  been  confidered  at  the  E-nglifti  tin- 
mines  as  a  ftone  containing  no  metal, 
until  fome  years  ago  it  began  to  be 
fmelted  to  great  advantage. 
j.  Cryftallifed. 

a.  Tin  fpar,  or  white  tin  ore.  This  is  ge 
nerally  of  a  whitifti  or  grey  colour  ;  forne- 
times  it  is  yellowifh,  femi-tranfparent, 
and  cfyftullifed,  either  of  a  pyramidical 
form,  or  irregularly. 

I.  Tin-grains.  This  ore,  like  the  garnets, 
is  of  a  fpherical  polygonal  figure;  but 
feems  more  unctuous  on  its  furface. 

1.  In  large  grains. 

2.  In  fmall  grains, 
j?.  Mixed  with  metals. 

I.  With 


C 

1.  With  the  calx  of  iron,  as  in  the  garnet. 

2.  With  manganefe.     See  the  Semimetals, 
C.  Mineralifed. l 

1.  With  fulphur  and  iron. 

2.  With  fulphur.      Aurum  mufivum. 

This  was  difcovered  by  ProfefTor  Berg 
man,  among  fome  minerals  which  he  recei 
ved  from  Siberia.  He  obferved  two  forts 
of  it,  analogous  to  the  two  artificial  combi 
nations  of  tin  with  fulphur. 

1.  One  nearly  of  the  colour  of  zinc,  and 
of  a  fibrous  texture,  which  contained 
about  20  per  cent,  of  fulphur,  and  the 
remainder  tin. 

2.  The  other  enveloped  the  former  like  a 
cruft  ;  refembled  aurum  mufivum  ;  and 
contained  about  4.0 per  cent,  of  fulphur,  a 
fmall  proportion  of  copper,  and  the  re 
mainder  tin.  Mem.StockLfor  1 7  2 1  ,p.  3  2  8. 

At  Huel  Rock,  in  St  Agnes  in 
Cornwall,  there  has  been  found  a  me 
tallic  vein,  nine  feet  wide,  at  20  yards 
beaeath  the  furface.  Mr  Rafpe  was 
the  firft  who  difcovered  this  to  be  a 
fulphurated  tin-ore  :  it  is  very  com 
pact,  of  a  bluilh  white  colour,  ap 
proaching  to  grey  fteel,  and  fimilar  to 
the  colour  of  grey  copper  ore:  it  is 
lamellar  in  its  texture,  and  very  brittle. 
It  confifts  of  fulphur,  tin,  copper,  and 
fome  iron.  Mr  Rafpe  propofes  to  cail 
it  bell-metal  ore. 

According  to  Mr  Klaproth's  ana- 
lyfis  of  this  ore,  119  grains  contain  30 
of  pure  fulphur  ;  41  of  tin ;  43  of  cop 
per  ;  two  of  iron  ;  and  three  grains  of 
the  Ilony  matrix.  In  another  fpeci- 
men.  of  the  fame  fulphurated  tin-ore 

iroin 


This  is  diftinguiihed  from  the  other  metals  by  the 

following  characters  and  qualities,     It  is, 

a.  Of  a  white  colour,  which  verges  more  to  the 

blue  than  that  of  filver. 
1.  It  is  the  rncft  fufible  of  all  metals  ;  and, 
c .  The    leaft  ductile  ;  that  is,  it  cannot  be  ex 
tended  or   hammered    out  fo    much    as  the 
others  (x). 

d.  In  breaking  or  bending,  it  makes  a  crack-*- 
ling  noife. 

e.  It  has  a  fmell  particular  to  itfelf,  and  which 
cannot  be  defcribed. 

f.  In  the  fire  it  is  eafily  calcined  to  white  afhes, 
which  are  25  per  cent,  heavier  than  the  me 
tal  itfelf.  During  this  operation,  the  phlo- 
gifton  is  feen  to  burn  off  in  form  of  fmall 
fparkles  among  the  aihes  or  calx. 


(x)  Tin  is  fufficiemly  ductile  to  be  beaten  into  very 
thin  leaves.  But  ductility  and  extenfibility  are  two  dif 
ferent  properties,  lefs  connected  with  one  another  than 
is  generally  imagined.  Iron  and  fteel  are  drawn  into 
exquifite  fine  wire,  but  cannot  be  beat  into  very  thin 
leaves.  Tin,  on  the  other  hand,  is  beat  into  fine  leaves, 
and  may  be  extended  between  rollers  to  a  confiderable 
furface.  The  tin-fheet  ufed  in  various  arts,  is  com* 
monly  about  7^ffth  part  of  an  inch  ;  but  may  be  ex 
tended  twice  as  much  in  its  dimenfions  without  diffi 
culty.  Notwithftanding  this  extenfibility,  tin  cannot  be 
drawn  into  wire,  on  account  of  the  weak  cohefion  of 
its  particles.  A  tin  wire,  however,  of  one-tenth  of 
an  inch  diameter,  is  able  to  fupport  a  weight  of  49^ 
pounds,  according  to  Fourcroy.  Gold  and  filver  poflefs 
both  properties  of  ductility  and  extenfibility  the  moft 
eminently  of  all  metallic  bodies ;  whilfl  lead,  notwith- 
ftanding  its  flexibility  and  foftnefs,  cannot  be  made  eU. 
tUerlnto  leaves  or  wire  ©f  any  finenefs* 

T  3  S>  Thfe 


j.  This  calx  is  very  refraclory  ;  but  may,  how 
ever,  with  a  very  ftrong  degree  of  heat  be 
brought  to  a  glafs  of  the  colour  of  colophony. 
But  this  calx  is  eafily  mixed  in  glafs  com- 
pofitions,  and  makes  with  them  the  white 
enamel. 

h.  It  unites  with  all  metals  and  femimetals ; 
but  renders  moft  of  them  very  brittle,  except 
lead,  bifmuth,  and  zinc. 
i.  It  amalgamates  eafily  with  quickfilver. 
k.  It  diffolves  in  aqua-regia,  the  fpirit  of  fea- 
falt,  and  the  vitriolic  acid ;  but  is  only  cor 
roded  into  a  white  powder  by  the  fpirit  of 
nitre.     The  vegetable  acid,  foaps,  and  pure 
alkaline  falts,  alfo  corrode  this  metal  by  de 
grees. 
/.  Its  fpecific  gravity  to  water  is  as  7400  to 

icoo,  or  as  7321  to  1000. 
m.  Diffolved  in  aqua-regia,  which  for  this  pur- 
pofe  ought  to  confift  of  equal  parts  of  the 
fpirit  of  nitre  and  fea-falt,  it  heightens  the 
colour  of  the  cochineal,  and  makes  it  deeper  j 
for  otherwife  that  dye  would  be  violet. 
(i.)  Native  Tin. 

The  exiftence  of  native  tin  has  long  been 
queliioned  :  but  it  has  undoubtedly  been  found 
feme  years  ago  in  Cornwall,  as  Mr  Kirwan 
remarks. 

3 .  Malleable  tin,  in  a  granular  form,  and  alfo  in 
,   a  foliaceous  fhape,  ifluing  out  of  a  white  hard 
matter   like  quartz  :    but  which,  after  being 
properly  aflfayed,  proved  to  be  arlenical  cry- 
Jlals ;  a  circumftance  that  evinces  its  being  na 
tive  tin,  fince  the    arfenic  could    not  remain 
in  this  form  if  the  tin  had  been  melted.     It 
appeared    like  a  thick,  jagged,    or  fcolloped 
lace  or  edging  j  and  was  found  near  St  Auftle 
in  Cornwall, 

2.  In 


r  *»$  3 

from  Cornwall,  there  were  in  the  hun 
dred  25  parts  of  fulphur,  34  of  tin,  36 
of  copper,  three  of  iron,  and  two  of 
the  ftony  matrix. 

II.  Lead  ;  Plumlum>  Saiurntu.     (See  the  article  LEAD, 
and    CHEMISTRY-/^/«C  .-     Aifo    METALLURGY, 
Part  II.  fed.  v.  and  Part  III.  fed*,  vii.) 
The  properties  of  lead  are  as  follows. 

a.   It  is  of  a  blui'h  white  colour  when  freih  broke, 

but  foon  dulls  or  follies  in  the  air. 
I.  It  is  very  heavy  j   viz.  to  water  as  11,325  to 

1COO. 

t*  It  is  the  fofteft  metal  next  to  gold  ;  but  it 
has  no  great  tenacity,  and  is  not  in  the  leaft 
fonorous, 

d<  It  is  eafily  calcined  j  and  by  a  certain  art  in 
managing  the  degrees  of  the  fire,  its  eal%  be 
comes  white,  yellow,  and  red. 

t.  This  calx  melts  eafier  than  any  other  metallic 
calx  to  a  glafs,  which  becomes  of  a  yellow  co 
lour,  and  femitranfparent.  This  glafs  brings 
other  bodies,  and  the  imperfect  metals,  into 
fufion  with  it. 

/.  It  diflblves,  ift,  In  the  fpirit  of  nitre  ;  2dly, 
In  a  diluted  oil  of  vitriol,  by  way  of  digeftion  ; 
3dly,  In  the  vegetable  acid ;  4thly,  In  alkaline 
folutions ;  and  5thly,  In  exprefied  oils,  both 

-    in  the  form  of  metal  and  of  calx. 

g.  It  gives  a  fweet  tafte;to  all  folutions. 

/j.  It  amalgamates  with  quickfilver. 

i.  With  the  fpirit  of  fea-falt  it  has  the  fame  ef 
fect  as  filver,  whereby  is  produced  a  faturnus 
corneuj. 

k.  It  does  not  unite  with  iron,  when  it  is  alone 
added  to  it  in  the  fire. 

/.  It  works  on  the  cupel,  which  fignifies  that  its 
glafs  enters  into  certain  porous  bodies,  defti- 
tute  ofphlogifton  and  alkaline  falts. 

m.  It 


t     216     ] 

m.  It  melts  in  the  fire  before  it  is  made  red-hot, 

almoft  as  eafilyas  the  tin. 
n.  Its  calx  or  glafs  may  be  reduced  to  its  metallic 

ftr,te  by  p<  t-afhes. 
i,]  Native  Lead. 

For  proofs  of  lead  being  naturally  found  in 
its  metallic  ftate,  fee  the  article  LEAD.-— It  may 
be  here  added,  that  Henckel  likewife  affirms  its 
exiftence,  in  his  Flora  Saturnifans  ;  (fee  Kinvan's 
Elements  of  Mineralogy,  p.  297,  298.)  Walle- 
rius  aflerts,  that  it  has  been  fo  found  in  Poland, 
a  fpecimen  of  which  war,  kept  in  the  collection  of 
Richter  ;  and  adds,  that  a  fimiiar  one  fr-und  at 
Schneberg,  was  ft  en  in  the  collection  of  Spener. 
(Mineralogy,  vol.  ii.  p.  301.) 

Dr   Lawfon,   in  his  Englifh  edition  of  Cra 
mer's  Art  of  Eifaying  Metals,  fays,  that  fume 
pure  native  malleable  lead  had  been  lately  found 
in  New  England;   (p.   147.)     And  kftly,  Pro- 
feffor  Bergrran  did  not  hefitate  to  infert,  by  it 
felf  alone,  the  plumbum  naiwum,  in  Seel.  180.  of 
his  Sciagraphies. 
2*~\  Calciform  Lead. 
Lead  is  found, 
^.  In  the  furm  of  a  calz. 

A.  Pure. 

a.  Friable  lead  ochre,  native  cerufe. 

b.  Indurated  lead  fpar,  or  fpatofe  lead  ore. 
i.  Radiated,  or  fibrous. 

i.  White,  from  Mendip-hills,  in  Eng 
land, 
ii.  Cryftallifed  in  a  prifmatic  figure, 

1.  White,  from  Norrgrufva  in  Weft- 
manland, 

2.  Yellowifh  green,  from  Zchopau  in 
Saxony. 

B.  Mixed. 

i.  White 


1.  With  the  calx  of  arfenic,  arfenical  lead 
fpar. 

2.  Indurated* 

a.  White.  Mr  Cronftedt  has  tried  fuch 
an  ore  from  an  unknown  place  in  Ger 
many,  and  found  tiiat  no  metallic  Aead 
could  be  melted  from  it  by  means  of 
the  blc'.v-pip?,  as  can  be  done  out  of 
other  lead  ipurs  ;  but  it  muft  be  per 
formed  in  a  crucible.  (See  the  article 
LEAD,  par.  ili.) 

3.  With  a  calcareous  earth. 

This  ore  efferveices  with  aqua-fortis,  and 
contains  40  per  cent,  of  lead  :  on  which 
account  it  is  placed  here  rather  than 
among  the  calcareous  earths. 
B.  Mineralifed. 

1.  With  fulphur  alone  :  the  bley-fck{witfft  or  bley 
gfanz,  of  the  Germans. 

a.  Steel-grained  lead  ore. 

b.  Radiated,  or  antimoniated  lead  ore. 
f.  TefTellated,  or  potter's  lead-ore. 

At  Villach  in  Auftria  there  is  faid  to  be 
found  a  potter's  lead-ore,  which  contains  not 
the  leafl  portion  of  filver. 

2.  Mineralifed  by  the  vitriolic  acid^ 

This  ore  was  difcovered  by  Mr  Monnet. 
It  occurs  fometimes,  though  rarely,  in  the 
form  of  a  white  ponderous  calx ;  and  feems 
to  originate  from  the  fpontaneous  decompoii- 
tion  of  t)ie  fulphurated  lead-ores  abovemen- 
tioned. 

3.  By  tie  acid  of  phofphorus. 

This  ore  was  lately  difcovered  by  Ghan ; 
and  is  of  a  greeniih  colour,  by  reafon  of  a 
mixture  of  iron.  See  the  article  LEAD, 
par.  6. 

4.  With  fulphurated  filver.     Galena  ;  alfo  called 

bkyglatm 


C    ."8     ] 

lleyglany,  by  the  Germans.     Potter's  ore. 

a.  Steel-grained. 

b.  With  fm all  fcales. 
€.  Fine-grained. 

d.  Of  a  fine  cubical  texture  ;  and, 

e.  Of  coarfe  cubes.     Thele  two  varieties  are 
found  in  all  the  Swedilh  filver-mines. 

/  Cryftallifed. 

The  fteel-grained  and  fcaly  ores  are  of  a 
dim  and  dull  appearance  when  they  are 
broken,  and  their  particles  have  no  deter 
mined  angular  figure  :  they  are  therefore  in 
Swedifti  commonly  called  blyfchwiif ;  in  op- 
pofition  to  the  cubical  ores,  which  are  call 
ed  blyglan-z.  The  moft  part  of  the  ores  call- 
ed  blyglanz  contain  filver,  even  to  24  ounces 
$er  cent,  of  which  we  have  inftances  in  the 
mines  of  Salberg,  where  it  has  been  obfer- 
ved,  that  the  coarfe  cubical  lead  ores  are  ge 
nerally  the  rich  eft  in  filver,  contrary  to 
what  is  commonly  taught  in  books;  the 
reafon  of  which  may  perhaps  be,  that,  in 
making  the  eflays  on  thofe  two  ores,  the 
coarfe  cubical  can  be  chofen  purer  or 
freer  from  the  rock  than  the  fine  cubical 
ores. 

5.  With  fulphurated   iron  and   filver.     This  is 
found, 

a.  Fine-grained,  b.  Fine  cubical,  c.  Coarfe- 
cubical..  When  this  ore  is  fcorified,  it  yields 
a  black  flag  ;  whereas  the  preceding  lead* 
ores  yield  a  yellow  one,  becaufe  they  do  not 
contain  any  iron. 

6.  With  fulphurated  antimony  and  filver  ;  anti- 
moniated  or  radiated  lead-ore.     This  has  the 
colour  of  a  bleyglanz,  but  is  of  a  radiated  tex 
ture. 

It  is  found, 


[     «9     ] 

a.  Of  fine  rays  and  fibres;  and,    . 

b.  Of  coarfe  rays  or  fibres.     The  lead  in  this 
ore  prevents  any  ufe  being  made  of  the  anti- 
many  to  advantage  ;  and  the  antimony  like- 
wife  in  a  great  meafure  binders  the  extrac 
ting  of  the  filver. 

^.  Mineralifed  by  arfenic 

This  ore  was  lately  difcovered  in  Siberia— 
Externally  it  is  of  a  pale,  and  internally  of 
a  deep  red  colour.  See  the  article  LEAD, 
par.  10. 

C.  Mixed  with  earth  ;  ftony,  or  fandy  lead  ores. 
Thefe  confill  cither  of  the  calcifbrm  or  of  the 
galena  kind,  intimately  mixed  and  diffufed 
through  ftones  and  earth,  chiefly  of  the  calca 
reous  or  of  the  barytic  genus.  See  LEAD^ 
par.  1 1 . 

Ufssy  &c.    of  Lead.     See     LEAD,    and    the    other 
articles  above  referred  to. 

III.  Copper;   Cuprum,   Venus,  JEs.     (See  the  article 
COPPER:  Alfo  CHEMISTRY-/;?^.*  ;  and  METAL 
LURGY,    Part   II.  fea.  iv.    and  Part   III.  fed. 
iv.) 
This  metal  is, 

a.  Of  a  red  colour. 

b.  It  is  pretty  foft  and  tough. 

c.  The  calx   of  copper  being  diflblved  by  acids 
becomes  green,  and  by  alkalies  blue. 

</.  It  is  eafily  calcined  in  the  fire  into  a  blackifh 
blue  fubftance,  which,  when  rubbed  to  a  fine 
powder,  is  red  ;  when  mdted  together  with 
glafs,  it  tinges  it  firft  reddifh  brown,  and  af- 
terw.irds  of  a  tranfparent  green  or  fea-green  co 
lour. 

*..  It  didblves  in  all  the  acids,  and  likewife  in  al 
kaline  folntions.  It  is  eafier  diffolved  when  in 
f^rm  of  a  c  dx  than  in  a  metallic  ft  ate,  efpeci- 
U  ally 


[       220       ] 

ally  by  the  acids  of  vitriol  and  fea-falt,  and  the 
vegetable  acid. 

f.  Vitriol  of  copper  is  of  a  deep  blue  colour;  but 
the  vegetable  acid  produces  with  the  ccpper  a 
green  fait,  which  is  verdigris. 

g.  It  can  be  precipitated  out  of  the  folutions  in  a 
metallic  (late  ;  and  this  is  the  origin  of  the  pre 
cipitated  copper  of  the    mines   called   Ziment 
copper. 

h.  It  is  not  eafi-ly  amalgamated  with  quickfilver  ; 
but  requires  for  this  purpofe  a  very  ftrong  tri- 
turation,  or  the  admixture  of  the  acid  of  nitre. 

«.  It  becomes  yellow  when  mixed  with  zinc,  which 
has  a  ftrong  attraction  to  it,  and  makes  brafs, 
pinchbeck,  £c. 

I.  When  the  metal  is  expofed  to  the  fire,  it  gives 
n.  green  colour  to  the  flame  in  the  moment  it 
begins  to  melt,  and  continues  to  do  fo  after 
wards,  without  lofing  any  thing  confiderable 
of  its  weight. 
£1.3  Native  copper. 

Copper  found  naturally  in  a  metallic  ftate,  is 
called  virgin  or  native  copper.  It  is  met  with, 

1.  Solid. 

2.  Friable,  in  form  of  fmall,  and  fomewhat  co 
herent  grains.     Precipitated  or  ziment  copper. 

£2.]  Calciform. 

Copper,  in  form  of  a  calx,  is  found, 
j.)  Pure. 

A.  Loofe  or  friable  ;  Ocbra  veneris. 

1 .  Blue  ;   Cceruleum  montanum.     Very  feldom 
found  perfectly  free  from  a  calcareous  fub-1 
ftance. 

2.  Gre'zn  ;    Viride  monlanum.     Both  this  and 
the  former   colour   depend  on  menftrua, 
which  often,  are  edulcorated    or  wafbed 
away. 

3.  Red. 


[       221        ] 

3.  Red.     This  is  an  efflorefcence  of  the  glafs 

copper  ore. 
B.  Indurated.     Glafs  copper-ore. 

a.  Red.  This  is  fometimes  as  red  as  feal 
ing  wax,  and  fometimes  of  a  more  liver- 
brown  colour. 

It  is  always  found  along  with  native 
copper,  and  feems  to  have  loll  its  phlo- 
giilon  by  way  of  efflorefcence,  and  to  be 
changed  into  this  form.  It  is  likewife 
found  with  the  iulphurated  copper,  impro 
perly  called  glafs  c  of  per  ere. 
2.)  Mixed. 

A.  Loofe  or  friable  ;  Oc/ira  vener  is  friab'ilis  im- 
pura. 

1.  Mixed  with  a  calcareous  fubilance,;  Cce- 
rukum  montanum.     In  this  (late  copper-blue 
is  moftly  found.     It  ferments  during,  the 
folution  in  aquafortis. 

2.  Mixed  with  iron.     Black.     It  is  the  de- 
compoiition  of  the  Fahlun  copper  ore. 

B.  Indurated. 

1.  Mixed  with  gypfum,  orplafler.     Gree?. 

2.  Mixed  with  quartz,     a.  Red,  from  Sun- 
nerfkog  in  the  province  cf  Smoland. 

3.  Mixed  with  lime.     a.  Blue.     This  is  the 
JLapis  Armenia  j  according  to  the  accounts 
given  of  it  by  authors. 

3.)  Cupreous  (lones. 

Analogous  to  the  calciform  copper  ores,  are, 

1.  The  lapis  ar/nenus.  1  See  the  detached  ar- 

2.  The  turquoife.       J    tide  COPPER,  n°  7. 


3.]  Diifolved  and  mineraiifedj    Cuprum 
fat  urn. 

A.  With  fulphur  alone.     Grey  copper-ore  ;  alfo 
called,  improperly,  g'afs  copper-ore. 
a.  Solid,  without  any  certain  texture,  and  very 
foft,  fo  that  it  can  be  cut  with  a  knife  almoft 
as  eafily  as  black  lead. 

U  2  b.  Fine 


222 

t.  Fine  cubical.     In   Smoland  this1  is   fome- 
times  found  dccompofcd  or  weathered,  and 
changed  into  a  deep  mountain  blue. 
».  With  fulphurated  iron.    Minera  cupri  pyntacea  / 
yellow  copper  ore.     Marcafitical  copper  ore  ; 
Pyrites  cupri.     This  is  various  both  in  regard  to 
fcolour  and  in  regard   to  the  different  propor 
tion  of  each  of  the  contained  metals ;  for  in- 
ftance, 

a.  Blackifh  grey,  inclining  a  little  to  yellow  ; 
Pyrites  cupri  grifeus.  When  decayed  or 
weathered,  it  is  of  a  black  colour  ;  is  the 
richeft  of  all  the  varieties  of  this  kind  of 
copper  ore,  yielding  between  50  and  60 
per  cent,  and  is  found  in  Spain  and  Ger 
many. 

I.  Reddifh  yellow,  or  liver  brown,  with  a  blue 
coat  on  the  furface ;  Minera  cupri  lazurea, 
This  ore  yields  between  40  and  5^0  per  cent. 
of  copper,  and  is  commonly  faidto  be  blue, 
though  it  is  as  »ed,  when  frefli  broken,  as  a 
red  copper  regulus. 

t.  Yellowifh  green  ;  Pyrites  cupri flavo  -viridefcens. 
This  is  the  moft  common  in  the  north  part  of 
Europe :    and  is,  in  regard  to  its  texture, 
found, 
r.  Solid,  and  of  a  mining  texture. 

2.  Steel  grained,  of  a  dim  texture. 

3.  Coarfe-grained,  of  an  uneven  and  finning 
texture. 

4.  Cryftallifed  marcafitical  copper  ore, 
a.  Of  long  octoedrtcal  cryftals. 

d.  Pale  yellow.     This  cannot  be  defcribed  but 
as  a  marcafite,  though  an  experienced  eye 
will  eafily  difcover  fome  difference  between 
them.     It  yields  22  per  cent,  of  copper. 

e.  Liver-coloured. 

c.  With  fulphurated  filver,  arfenic,  a<nd  fome  iron, 
Fallow  copper-or&j  which  contains  only  a  few 

ounces 


ounces  of  filver.  *This  ore  is  found  iri  Hunga 
ry  and  Germany,  where  it  is  called  black  topper 
ore, 

D.  With  fulphurated  arfenic  andiron.  'White cop 
per  ore. 

E.  Pyritous  copper,  -with  arfenic  and  zinc. 

According  to  Mr  Monnet,  this  ore  is  found 
at  Catliarineberg  in  Bohemia.  It  is  of  a  brown 
colour  ;  of  a  hard,  folid,  compact,  granular 
texture  ;  and  contains  from  1 8  to  30  per  cent. 
of  copper. 

F.  DifTolved  by  the   vitriolic  acid ;    Witriolum  *os- 
neris.     See  the  article  copper,  n°  xriii. 

c.  With  phlogifton.  Copper  coal  ore,  confiding 
of  the  calces  of  copper,  mixed  with  a  bitumi 
nous  earth. 

H,  Mineralifed  by  the  muriatic  acid.  This  ore 
was  found  in  Saxony,  and  had  been  generally 
rniftaken  for  a  micaceous  fubftance,  which  in 
fact  it  greatly  refembles.  It  has  not  yet  been 
found  in  large  maffes,  but  only  in  a  fupeificial 
form,  like  a  cruft  over  other  ores.  It  is  mo«- 
derately  hard  and  friable  ;  of  a  fine  green  co 
lour,  and  fometimes  of  a  bluiih  green,  cry- 
ftallifed  in  a  cubic  form,  or  with  a  foliated 
texture,  or  in  little  fcales  refembling  green 
mica  or  talc.  This  ore  is  eanly  diilblved  by 
nitrous  acid  :  the  folution  takes  a  green  colour  ; 
arid  the  metal  may  be  precipitated  en  a  po- 
IHhed  plate  of  iron.  If  fome  drops  of  a  ni 
trous  lolution  of  filver  be  mixed  with  it,  a 
white  powder  of  hna  cornea  will  bs  precipita 
ted,  which  difcovers  the-  prefence  of  the  muria 
tic  acid  in  this  ore. 

The  ufes  of  copper  are  very  numerous,  although 

not  thoroughly  known  to  every  one.     Several  of 

thefe  have  been  mentioned  under  the  detached 

U  5  article, 


[     "4     J 

article,  and  in  CHEMISTRY.  Others  of  great  im 
portance  may  be  here  added.  Its  great  ducYilky, 
lightnefs,  ftrength,  and  durability,  render  it  of  very 
extenfive  utility.  Blocks,  or  bars  of  copper,  are 
reduced  into  flat  fheets  of  any  thicknefs,  by  being 
firft  heated  by  the  reverberation  of  the  flame,  in 
a  low  vaulted  furnace,  properly  confliructed  for 
the  purpofe ;  and  then  immediately  applied  be 
tween  large  rollers  of  fteel,  or  rather  of  cafe-har 
dened  iron,  turned  by  a  water-wheel  or  by  the 
frrength  of  hcrfes,  fo  that  the  hot  metal  is  there 
quickly  fqueezed  ;  and  the  operation  is  repeated, 
bringing  the  rollers  every  time  nearer  to  one  an 
other,  till  the  metallic  iheet  acquires  the  intended 
thicknefs. 

Thefe  copper  fheetS  are  very  advantageoufly  em 
ployed  in  fneathing  the  bottoms  of  men  of  war 
and  other  veiTels,  which  by  this  means  are  pre 
vented  from  being  attacked  by  the  fea  worms, 
and  are  kept  clean  from  various  marine  concre 
tions,  fo  as  to  fail  with  confiderably  greater  fwift- 
nefs.  Copper  iheets  are  alfo  employed  to  cover 
the  tops  of  buildings  iiul^ad  of  flates  or  earthen 
tiles,  as  is  ufed  in  Sweden ;  and  fome  architects 
have  begun  to  introduce  the  life  of  copper  cover 
ing  into  Great  Britain,  which  is  much  lighter, 
and  may  be  ufed  with  great  advantage,  although 
it  inuft  be  much  dearer  in  prime  cod. 

Sundry  preparations  of  copper  are  employed  in 
painting,  Raining,  and  for  colouring  glafs  and 
enamels.  See  GLASS  and  ENAMEL.  ' 

The  folution  of  copper  in  aqua-fortis  ftains  marble 
and  other  ftones  of  a  green  coleur  ;  when  preci 
pitated  with  chalk  or  whiting,  it  yields  the 
green  and  the  blue  verditer  of  the  painters,  Ar- 
cording  to  Lewis,  a  folution  of  the  fame  metal 
in  volatile  fpirits  ftains  ivory  and  bones:  when 
macerated  for  fome  time  in  the  liquor,  they  be 
come 


C    225    ] 

come  of  a  fine  blvie  colour,  which,  however,  tar- 
nifhes  by  expofure  to  the  air,  and  becomes  green 
afterwards. 

The  fame  author  prepared  elegant  blue  glafTes,  by 
melting  common  glafs,  or  powdered  flint  and  fix 
ed  alkaline  fait,  with  blue  vitriol,  and  with  an 
amalgam  of  copper  ;  fine  green  ones  were  made 
with  green  verditer,  and  with  blue  verditer,  as 
well  as  with  the  precipitate  of  copper  made  by 
iixed  alkalies,  and  with  a  precipitate  by  zinc  ;  and 
a  reddifb  glafs  was  produced  by  the  calx  and  fco- 
ria  of  copper  made  by  fire  alone.  Even  in  this 
vitreous  (late,  it  feems  as  if  a  continuance  of  fire 
had  the  fame  effect  in  rega'rd  to  colour,  as  air  has 
upon  copper  in  other  forms  ;  as  fome  of  the  moft 
beautiful  blue  glafTes,  by  continued  fufion,  have 
changed  to  a  green  colour.  See  farther  the  article 
BRASS  in  the  Glafs -trade. 

Verdegris  is  a  preparation  of  copper  diflolved  by 
the  vegetable  acids,  which  act  on  this  metal,  dif- 
folving  it  very  {lowly,  but  in  confiderable  quanti 
ties.  It  produces  a  fine  green  pigment  for  paint 
ing  both  in  oil  and  water  colours,  inclining  more 
or  lefs  to  the  bluidi  according  to  circumilances. 

So  great  is  the  tenacity  of  copper,  that  a  wire  of 
a  tenth  of  an  inch  in  diameter  is  capable  of Sup 
porting  299.5  potfftds  weight  before  it  breaks. — • 
Copper  may  be  drawn  into  very  fine  wire,  and 
beaten  into  extremely  thin  plates.  The  German 
artifts,  chiefly  thofe  of  Nurenberg  and  Aufburg, 
are  faid  to  poiTefs  the  beft  method  for  giving  to 
thefe  thin  plates  of  copper  a  fine  yellow  colour 
like  that  of  gold.  See  the  articles  BRASS- Colour 
and  BzASS-Leaf. 

The  parings  or  fhreds  of  thefa  very  thin  leaves  of 
yellow  copper  being  well  ground  on  a  marble 
plate,  are  reduced  to  a  powder  fimilar  to  gold, 
which  ferves  to  cover,  by  means  of  fome  gum- 
water, 


t 

water,  or  othdr  adhefive  fluid,  the  furface  of  va 
rious  moulding  or  other  pieces  of  curious  Work- 
manfhip,  giving  them  the  appearance  of  real 
bronze,  and  even  of  fine  gold1;  ^t  a  Very  trifling 
expence  ;  becaufe  the  gold  colour  of  this  metallic 
powder  may  be  eafily  raifed  and  improved  by 
ftirring  it  on  a  wide  earthen  bafon  over  a  flow 
fire. 

In  fome  of  its  ftates,  copper  is  as  difficulty  ex 
tended  under  the  hammer  as  iron,  but  proves 
fofter  to  the  file,  and  never  can  be  made  hard 
enough  to  ftrike  afpark  with  flint  or  other  ftones  ; 
from  whence  proceeds  the  ufe  that  is  made  of  this 
metal  for  chifels  hammers,  hoops,  &c.  in  the 
gun-powder  works. 

*lhe  vitriolic  acid  does  not  aft  on  copper  unlefs 
concentrated  and  boiling  :  during  this  folution  a 
great  quantity  of  fulphureous  gas  flies  off;  after 
wards  a  brown  thickifh  matter  is  found,  which 
contains  the  calx  of  the  metal  partly  combined 
with  the  acid.  By  folution  and  filtration,  a  blue 
folution  is  obtained,  which  being  evaporated  to  a 
-certain  degree,  produces  after  cooling  long  rhom- 
iboidal  cryftals  of  a  beautiful  blue  colour,  called 
vitriol  of  copper  ;  but  if  this  folution  be  merely 
expofed  a  long  time  to  the  air,  it  affords  cryftals, 
and  a  green  calx  is  precipitated,  a  colour  which 
all  calces  of  this  metal  aflume  when  dried  by  the 
air.  Blue  vitriol,  however,  is  feldom  formed  by 
diffolving  the  metal  diredlly  in  the  vitriolic  acid. 
That  fold  in  the  fliops  is  moflly  obtained  from 
copper  pyrites.  It  may  alfo  be  made  by  ftratify- 
ing  copper-plates  with  fulphur,  and  cementing 
them  together  for  fome  time  ;  becaufe  the  vitrio 
lic  acid  of  the  fulphur  being  difengaged,  attacks 
and  corrodes  the  metal,  forming  a  metallic  fait, 
w'hich  by  affufion  of  water  yields  perfect  cryftals 
of  blue  vitriol.  Se'e  VITRIOL. 

The 


I      M.7.      J 

The  nitrous  acid,  on  the  contrary,  diflblves  copper 
•when  cold  with  great  rapidity  ;  and  a  great  quan 
tity  of  fmoaking  air  or  gas  flies  off,  which,  on 
being  received  in  a  pneumatic  apparatus,  and 
mixed  in  a  glasfs  tube  with  atmofphefic  air,  ftiows 
its  go©d  or  bad  quality  for  the  refpiration  of  li 
ving  animals,  according  as  the  common  bulk  is 
more  or  lefs  dirniniihed.  This  is  one  of  the  moft 
important  of  Dr  Prieftley's  difcoveries  ;  and  va 
rious  instruments  known  by  the  name  of  eudiome 
ters  have  been  fmee  invented  for  making  thefe  ex 
periments  with  eafe  and  fatisfatfion.  See  EUDIO 
METER. 

But  the  moft  common  ufe  of  copper  is  to  make  all 
ibits  of  large  ftills,  boilers,  pots,  funnels,  and 
other  veflels  employed  by  diRillers,  dyers,  che- 
rnifts,  and  various  other  manufacturers,  who  make 
ufe  of  large  quantities  of  hot  liquors  in  their  va 
rious  operations. 

Although  copper  when  pure  is  extremely  valuable, 
on  account  of  its  ductility,  lightnefs,  and  ftrength, 
it  is,  however,  lefs  ufeful  on  many  occafions  from 
the  difficulty  of  forming,  large  maifes  of  work, 
as  it  is  not  an  eafy  matter  to  cad  copper  folid,  fo 
as  to  retain  all  its  properties  entire.  For  if  the 
heat  be  not  fwfficiently  great,  the  metal  proves 
deficient  in  toughnefs  when  cold  ;  and  if  the  heat 
be  raifed  too  higfe,  or  continued  for  a  le.ngth  of 
time,  the  copper  blifters  on  the  furface  when  caft 
in  the  moulds :  fo  that  the  limits  of  itsfufion  are 
very  contracted.  And  from  thefe  circumibnces 
.pure  copper  is  rendered  lefs  applicable  :o  feveral 
purpofes. 

We  find,  however,  that  the  addition  of  a  certain 
proportion  of  zinc  removes  alrnoft  all  thefe  incon 
veniences,  and  furnifhes  a  mixed  metalmore  fu- 
f'blethan  copper,  very  ductile  and  tenacious  when 
cold;  which  does-  not  fo  readily  fcorify  in  a  mode-' 

rate 


E    "8    j 

rate  heat,  and  which  is  lefs  apt  to  ruil  from  the 
action  of  air  and  moifture. 

Copper  is  the  bafis  of  fundry  compound  metals 
for  a  great  number  of  mechanical  aad  ceconomi- 
cal  ufes  of  life,  fuch  as  brafs  (Y),  prince's-metal, 


(Y)  Brafs  is  frequently  made  by  cementing  plates 
of  copper  with  calamine,  where  the  copper  imbibes 
one-fourth  or  one-fifth  its  weight  of  the  zinc  which  ri 
tes  from  the  calamine.  The  procefs  confifts  in  mix 
ing  three  parts  of  the  calamine  and  two  of  copper  with 
charcoal  dud  in  a  crucible,  which  is  expofed  to  a  red 
heat  for  fome  hours,  and  then  brought  to  fufion .  The 
vapours  of  the  calamine  penetrate  the  heated  plates  of 
copper,  and  add  thereby  to  its  fufibility.  It  is  of 
great  confluence  for  the  fuccefs  of  this  procefs  to 
have  the  copper  cut  into  irnall  pieces,  and  intimately 
blended  with  the  calamine.  See  CHEMISTRY,  n°  1 151,. 

In  moft  foreign  founderies  the  copper  is  broken  frnall 
by  mechanical  means  with  a  great  deal  of  labour  ;  bu-t 
at  Briftol  the  workmen  employ  an  eafier  method.  A 
pit  is  dug  in  the  ground  of  the  manufactory  about  four 
feet  deep,  the  fides  of  which  are  lined  with  wood.  The 
bottom  is  made  of  copper  or  brafs,  and  is  moveable  by 
means  of  a  chain.  The  top  is  made  alfo  of  braf?  with  a 
fpace  near  the  centre,  perforated  with  fmall  holes,  which 
are  luted  with  clay;  through  them  the  melted  copper  is 
poured,  which  runs  in  a  number  of  ftreams  into  the  wa 
ter,  and  this  is  perpetually  renewed  by  a  freih  dream 
that  pafles  through  the  pit.  As  the  copper  falls  dowry 
it  forms  itfelf  into  grains,  which  collect  at  the  bot 
tom.  But  great  precaution  is  required  to  hinder  the 
dangerous  explofions  wbich  melted  copper  produces 
when  thrown  into  cold  water ;  which  end  is  obtained  by 
pouring  fmall  quantities  of  the  metal  at  once.  The 
granulated  copper  is  completely  mixed  with  powder 
ed  calamine,  and  fufed  afterwards.  The  procefs  lafts 

eight 


C 

tombac,  bell-metal,  white  copper,  &c.  See  CHE 
MISTRY,  n°  1154,  &c. 

If  the  mixture  is  made  of  four  to  fix  parts  of  cop 
per,  with  one  part  of  zinc,  it  is  called  Prince' s-me- 
tal.  If  more  of  the  copper  is  taken,  the  mixture 


eight  or  ten  hours,  and  even  fome  days,  according  to 
the  quality  of  the  calamine. 

It  is  a  wonderful  thing,  fays  Cramer,  that  zinc  it- 
felf,  being  fimply  melted  with  copper,  robs  it  of  all 
its  malleability  ;  but  if  it  be  applied  in  form  of  vapour 
from  the  calamine,  the  fublimates,  or  the  flowers,  it 
does  not  caufe  the  metal  to  become  brittle. 

The  method  mentioned  by  Cramer  to  make  brafs 
from  copper,  by  the  volatile  emanations  of  zinc,  feems 
to  be  preferable  to  any  other  procefs,  as  the  metal  is 
then  preferved  from  the  heterogeneous  parts  contain 
ed  in  the  zinc  itfelf,  or  in  its  ore.  It  confifts  in  mixing 
the  calamine  and  charcoal  with  moiftened  clay,  and 
ramming  the  mixture  to  the  bottom  of  the  melting  pot, 
on  which  the  copper,  mixed  alfo  with  charcoal,  is  to 
be  placed  above  the  rammed  matter.  When  the  pro 
per  degree  of  heat  is  applied,  the  metallic  vapour  of 
the  zinc  contained  in  the  calamine  will  tranfpire 
through  the  clay,  and  attach  itfelf  to  the  copper,  lea 
ving  the  iron  and  the  lead  which  were  in  the  calamine 
retained  in  the  clay,  without  mixing  with  the  upper, 
metal,  Dr  Watfon  fays  that  a  very  good  metallurgifl 
of  Briftol,  named  John  Champion,  has  obtained  a  patent 
for  making  brafs  by  combining  zinc  in  the  vapourous 
form  with  heated  copperplates  ;  and  that  the  brafs  from 
this  manufacture  is  reported  to  be  of  the  fined  kind  ;  but 
he  knows  not  whether  the  method  there  employed  is 
the  fame  with  that  mentioned  by  Cramer. 

Brafs  isfometimes  made  in  another  way,  by  mixing 
the  two  metals  diieclly ;  but  the  heat  requisite  to  melt 
the  copper  makes  the  zinc  burn  and  flame  out,  by  which 

the 


C    230    ] 

wiU  be  of  a  deeper  yellow,  and  then  goes  by  the 
name  of  tombac. 

Bell-metal  is  a  mixture  of  copper  and  tin,  forming 
a  compound  extremely  hard  and  fonoiouvmd  is 
lefs  fubject  to  alterations  by  expofure  ti>  the  air 
than  any  other  cheap  metal.  On  this  account  it 
is  advantageoufly  employed  in  the  fabrication  of 
various  utenfils  and  articles,  as  cannons,  bells,  fta- 
tues,  &c.  in  the  compofition  of  which,  however, 
other  metals  are  mixed  in  various  proportions,  ac 
cording  to  the  fancy  and  expei  ience  of  the  artift. 

White-copper  is  prepared  with  arfenic  and  nitre,  as 
mentioned  under  CHEMISTRY,  n°  1157. 

But  the  principal  kind  of  white-copper  is  that  with 
which  fpeculums  of  reflecting  telefcopes  are  made. 
See  the  article  SPECULUM. 

VII.  Iron  ;  Ferrum,  faars.     This  metal  is, 

a.  Ofablackifh  blue  fhining  colour. 

b.  It    becomes    duclile  by  repeated  heating  be 
tween  coals  and  hammering. 

f.  It  is  attracted  by  the  loadftone,  which  is  an 
iron  ore  ;  and  the  metal  itfelf  may  alfo  be  ren 
dered  magneticaL 

d.  Its 


the  copper  is  defrauded  of  the  due  proportion  of  zinc. 
If  the  copper  be  melted  feparately,  and  the  melted  zinc 
poured  into  it,  a  confiderable  and  dangerous  explofion 
ettfues ;  but  if  the  zinc  is  only  heated  and  plunged 
into  the  copper,  it  is  quickly  imbibed  and  retained. 
^The  union,  however,  of  thefe  two  metals  fucceeds  better 
if  the  flux  compofed  of  inflammable  fubftances  be  firft 
fufed  in  the  crucible,  and  the  copper  and  zinc  be  poured 
into  it.  As  foon  as  they  appear  thoroughly  melted, 
they  are  to  be  well  ftirred,  and  expedttioufly  poured  our, 
or  elfe  the  zinc  will  be  inflamed,  and  leave  the  red  cop 
per  behind.  2 


•a.  Its  fpecific  gravity  to  water  is  as  7,645,  or 

8000 :  1000. 
e.   It  calcines  eafily  to  a  black  fcaly  calx,  which, 

when  pounded,  is  of  a  deep  red  colour. 
/.  When  this  calx  is   melted  in  great  quantity 
with  glafs   compofitions,  it  gives   a    blackifti 
brown  colour  to  the    glafs ;    but  in  a   fmall 
quantity  a  greenifh  colour,  which  at  lafl  va- 
nifhes  if  forced  by  a  ftrong  degree  of  heat. 
g  It  is  diflblved  by  all  falts,  by  water,  and  like- 
wife  by  their  vapour.     The  calx  of  iron  is  dif* 
folved  by  the  fpirit  of  fea-falt  and  by  aqua- 
regia. 

1.  The  calx  of  the  di/Tolved  metal  becomes  yel 
low,  or  yellowifh  brown :  and  in  a  certain  de 
gree  of  heat  it  turns  red. 

i.  The  fame  calx,  when  precipitated  from  acids 
by  means  of  the  fixed  alkali,  is  of  a  greenifh 
colour ;  but  if  becomes  blue  when  precipitated 
by  means  of  an  alkali  united  with  phlogifton  ; 
in  which  laft  circumftance  the  phlogifton  unites 
with  the  iron  :  thefe  two  precipitates  lofe  their 
colour  in  the  fire,  and  turn  brown. 
L  The  vitriol  of  iron  is  brown. 

Iron  is  found, 

£  i.j  Native.     See  the  detached  article  IRON. 
l_2.~]  Inform  of  calx. 
A.  Pure. 

A.  Loofe  and  friable.     Martial  ochre ;   Miners. 
ochracea. 

i.  Powdery;  Qchra  ferrl.  This  is  commonly 
yellow  or  red,  and  is  iron  which  has  been 
diffolved  by  the  vitriolic  acid> 
-2.  Concreted.     Bog-ore. 

a.  In  form  of  round  porous  balls. 
I.  More  folid  bars. 

c.  In  fmall  flat  pieces,  like  cakes  or  pieces 
of  money. 

X  d.  In 


d.  In  fmail  grains. 

e.  In  lumps  of  an  indeterminate  figure. 
All  thefe  are  of  a  blackiih  brown,  or  a  light 

brown  colour. 

,  Indurated.     The  blood-ftone  ;  Hematites. 
( i . )  Of  an  iron  colour ;  Hematites  azrulefcens : 
This  is  of  a  bluifli  grey  colour";  it  is  not 
attracted  by  the   loadftone,  yields   a  red 
powder  when  rubbed,  and  is  hard. 

a.  Solid,  and  of  a  dim  appearance  when 
broken. 

b.  Cubical,  and  of  a  (liming  appearance 
when  broken. 

c.  Fibrous,  is  the  molt  common  torrjlen  of 
Sweden. 

d.  Scaly  :   the  elfenram  of  the  Germans. 

1.  Black. 

2.  Bluifli   grey.     When  this  is  found 
along  with  marcafite,  it  is  not  only 
sittracled  by  the  loadftone,  but  is  of 
itfelf  really  aloadPcone. 

c.  Cryftallifed. 

1.  In  ocloedrical  cryftals. 

2.  In  polyedrical  cryftals. 

3.  In  a  cellular  form. 

Thefe  varieties  are  the  moft  common  in 
Sweden,  and  are  very  feldoin  blended 
with  marcafite  or  any  other  heteroge 
neous  fubftance  except  their  different 
beds.  It  is  remarkable,  that  when  thefe 
ores  are  fousd  along  -with  marcafite, 
thofe  particles  which  have  lain  nearel 
to  the  marcafite  are  attracted  by  the 
loadftone,  although  thsy  yield  a  red  or 
reddiOi  Ijrown  powder,  like  thofe  which 
are  not  attracted  by  the  load-ftone  :  it 
is  like  wife  worth  obfervation,  that  they 
generally  contain  a  little  fulphur,  if  they 
are  imbedded  in  a  limePtone  rock. 


C    233    ] 

(2.)  Blackifii  brown  bloodftone  ;  Hematites 
nigrefcens.  Kidney  ore.  This  yields  a  red 
or  brown  powder  when  it  is  rubbed  ;  it 
is  very  hard,  and  is  attracted  by  the  load- 
ftone. 

a.  Solid,  with  a  glafiy  texture. 

b.  Radiated. 

c.  Cryftallifed. 

1.  In  form  of  cones,  from  Siberia. 

2.  In  form  of  concentric    balls,    with 
a  facetted   furface.     Thefe  are  very 
common    in     Germany,    but     very 
fcarce  in  Sweden. 

(3.)  Red  blood  done;  Hamatltes  Ruler.  Red 
kidney  ore. 

a.  Solid,  and  dim  in  its  text'.ire. 

b.  Scaly.      The  ilftnram  cf  the  Germans. 
This  is  commonly  found  along  with  the 
iron-coloured  iron  g'immsr,  and  fmears 
the  hands. 

tf.  Crydallifed,  in  concenuie  balls,  \vitha 

fiat  or  facetted  furface. 
(4.)  yellow  blood-done ;  Htmatites  Jtat>us. 

a.  Solid. 

b.  Fibrous. 

The  varieties  of  the  colours  in  the  blood-done 
are  the  fame  with  thofe  produced  in  the 
calces  of  iron  made  by  dry  cr  liquid  men- 
flrua  and  afterwards  expofed  to  different 
degrees  of  heat. 
13.  Mixed  with  heterogeneous  fubftances. 

A.  With  a  calcareous  earth.     White  fpathofe 
iron  ore.     Thejlahljkifi  of  the  Germans. 

B.  With  a  filicecus  earth.     The  martial  jafper 
of  Sinople. 

c,  With  a  garnet  earth.     Garnet  and  cockle 

or  fhirl. 
D.  With  an  argillaceous  earth.     The  bole. 

X  2  E.  With 


C    *34   J 

E.  With  a  micaceous  earth.     Mica. 

F.  With  manganefe. 

G.  With  an  alkali  and  phlogifton.     Blue  mar 
tial  earth.     Native  Pruffian-like  blue. 

i.  Loofe  or  powdery. 

H.  With  an  unknown  earth,  which  hardens  in, 
water.     Tarras ;   Ccmentum. 

1 .  Loofe  or  granulated ;   Terra  Puzzolana. 
This  is  of  a  reddifh  brown  colour,  is  rich 
in  iron,  and  is  pretty  fuiible. 

2.  Indurated  ;   Cementum  induratum.     This  is 
of  a  whitiih  yellow  colour,  contains  like- 
\vife  a  great  deal  of  iron,  and  has  the  fame 
quality  with  the  former  to  harden  foon  in 
water  when   mixed  with  mortar.     This 
quality  cannot  be  owing  to  the  iron  alone, 
but  rather  to  fome  particular  modification 
of  it  occafioned  by  fome  accidental  caufes,, 
bccaufe  thefe  varieties  rarely  happen  at 
any  othor  places  except  where  volcanoes 
huvs  been,  or  are  yet*  in  the  neighbour 
hood. 

[3.]  DiiTolved  or  mineralifed. 
A.  With  fulphur  alone. 

A.  Perfectly  faturated  ;  Ferrum  fulfhure  faturct' 
turn.     Marcafite. 

B.  With  very  little  fulphur.     "Black. iron  ore. 
Iron  ftone. 

This  is  either  attracted  by  the  loadftone, 
or  is  a  loadftone  itfelf  attracting  iron  ;  it  re- 
fembles  iron,  and  yields  a  black  powder  when 
rubbed. 

i.)    Magnetic    iron    ore.     The    loadftone, 
Magnes.  . 

a.  vSteel-grained,  of  a  dim  texture,  from 
Hogberget  in  the  parifh  of  Gagncef 
in  Dalarne :  it  is  found  at  that  place 
almoil  to  the  day,  and  is  of  as  great 

ftrength 


C    235    3 

ftrength  as  any  natural  loadilones  wees 
ever  commonly  found. 

b.  Fine  grained,  from  Saxony. 

c.  Coarfe-grained,  from  Spetaligrufvan  at 
Norberg,  and  Kierrgruivan,  both  in  the 
province  of  Weftmanland.     This  lofes 
very  foon  its  magnet ical  virtue. 

d.  With  coarfe  fc  lies,  found  at  Sandfwoer 
in  Norway.     This  yields  a  red  powder 
when  rubbed. 

2.)   Refractory  iron  ore.     This  in  ks  crude 
ftate  is  attracted  by  the  Icadftone. 
a.  Giving  a  black  powder  when  rubbed  j 
Trifura  aira.     Of  this  kind  are, 

1.  Steel-grained. 

2.  Fiae  grained. 

3.  Coarfe  grained. 

This  kind  is  found  in  great  quantities 
in  ail  the  Swedifh  iron  mines,  and  of  this 
moil  part  of  the  fnfible  ores  confift,  be- 
caufe  it  is  commonly  found  in  iuch 
kinds  of  rocks  as  are  very  fulible  :  and 
it  is  as  feldom  met  with  in  quartz  as 
the  hxmatites  is  met  \vith  in  lime- 
flone* 

I.  Rubbing  into  a  red  powder.  Thefe  are 
real  hcernatites,  that  are  fo  far  modified 
by  fulphur  or  lime  as  to  be  attrafted 
by  the  kadftone. 

1.  Steel-grained. 

2.  Fine-grained.    Emery.    This  k  im 
ported  from  the  Levant :.  it  is  mned. 
with   mica,  is  ftrongly  attracted  by 
the  loadllone,  and  fmells  of  fulphur 
•when  put  to  the  fire. 

3.  Of  large  iliining  cubes. 

4.  Coarfe,  Scaly.     The  c'if.ngHmmer  or 

X  3  [4.]  Mixed. 


C     23^    3 

[4-0  Mixed  with  various  foifile  fubftances. 

1.  With  fulphur  and  clay  ;  Pyrites. 

2.  With  arfenic  ;  called  mlfptckel  by  the  Germans, 
and  plate  mundic  in  Cornwall. 

3.  With  fulphurated  arfenic.     Arfenical  pyrites. 

4.  With  vitriolic  acid.     Martial  vitriol. 

5.  With  phlogifton.     Martial  coal  ore. 

6.  With  other  fulphurated  and  arfenicated  metals, 
See  thefe  in  their  refpeclive  arrangements. 

Ufss  and  Properties  of  Iron.  Iron  is  the  mod  com 
mon  metal  in  nature,  and  at  the  fame  time  the 
rnoft  ufeful  in  common  life ;  notwithstanding 
which,  its  qualities  are  perhaps  very  little  known. 

Iron  has  a  particular  and  very  fenfible  fmell  when 
ftrongly  rubbed  or  heated  ;  and  a  ftyptic  tafte, 
which  it  communicates  to  the  water  in  which  it 
is  extinguifhed  after  ignition.  Its  tenacity,  duc 
tility,  and  malleability,  are  very  great.  It  exceeds 
every  other  metal  in  elafticity  and  hardnefs,  when 
properly  tempered.  An  iron  wire  of  one-tenth 
of  an  inch  thick  is  able  to  fupport  450  pounds 
weight  without  breaking,  as  Wallerius  afferts. 

Iron  drawn  into  wire  as  (lender  as  the  fineft  hairs. 
It  is  more  eafily  malleable  when  ignited  than 
when  cold  ;  whereas  other  metals,  though  ductile 
when  cold,  become  quite  brittle  by  heat. 

It  grows  red-hot  fooner  than  other  metals ;  never- 
thelefs  it  melts  the  moft  difficultly  of  all,  platina 
and  manganefe  excepted.  It  does  not  tinge  the 
flame  of  burning  matters  into  bluifh  or  greeniih 
colours,  Uke  other  imperfect  metals,  but  brightens 
and  whitens  it ;  hence  the  filings  of  iron  are  ufed 
in  compofitions  of  fire-works,  to  produce  what  is 
called  <wbite-fire. 

Iron,  or  rather  fteel,  expands  the  lead  of  all  hard 
metals  by  the  action  of  heat;  but  brafs  expands 
the  mod  :  and  on  this  account  thefe  two  metals 
are  employed  in  the  conftru&ion  of  compound 

pendulums 


[    237     3 

pendulums  for  the  beft  fort  of  regulating  clocks 
for  aftronomical  purpofes 

Iron,  in  the  act  of  fufion,  inftead  of  continuing  to 
expand,  like  the  other  metals,  (brinks,  as  Dr 
Lewis  obferves  ;  and  thus  becomes  fo  much  more 
denfe  as  to  throw  up  fuch  part  as  is  unmeked 
to  the  furface  ;  whilft  pieces  of  gold,  filver,  cop 
per,  lead,  and  tin,  put  in  the  refpeclive  metals  in 
fulion,  fmk  quickly  to  the  bottom.  But  in  its 
return  to  a  confident  (late,  inftead  of  fhrinking, 
like  other  metals,  it  expands  ;  fenfibly  rifing  in  the 
veflel,  and  aflaminga  convex  furface,  whilft  the 
others  fubfide,  and  appear  concave.  This  pro 
perty  of  iron  was  firft  taken  notice  of  by  Reamur, 
and  excellently  fits  it  for  receiving  impreffions 
from  the  moulds  into  which  it  is  caft,  being  for 
ced  into  their  minuteft  cavities.  Even  when, 
poured  thick  into  the  mould,  it  takes,  neverthe- 
leis,  a  perfect  impreffion  ;  and  it  is  bferved,  that 
cad  iron  is  fo  me  what  larger  than  the  dimenfions 
of  the  mould,  whilft  caft  figures  of  other  metals 
are  generally  fmaller. 

The  vitriolic  acid  diifolves  iron  readily,  and  forms 
green  vitriol. 

This  acid  requires  to  be  diluted  with  304  times  its 
quantity  of  water,  to  enable  it  effectually  to  dif- 
folveiron;  and,  during  the  diflblution;  a  ftrong 
aerial  fluid  arifes,  called  inflammable  air,  which,  on 
being  mixed  with  atm&ipheric  air,  takes  fire  at 
the  approach  of  the  flame  of  a  candle.  A  glafs 
phial,  of  about  two  ounces  meafure,  with  one 
third  of  inflamHiable  air,  and  the  reft  of  common 
air,  produc.es  a  very  loud  report  if  opened  in  the 
lame  circumftance  ;  and  if  it  be  filled  with  two- 
thirds  of  inflammable  air,  mixed  with  one  of  de- 
phlogifticated  air,  the  report  will  be  as  loud  as 
the  explofion  of  a  piftol  with  gunpowtler. 

Dilute  nitrous  acid  dilfblves  iron  j  but  ibis  faline 

combina- 


C    238    3 

combination  is  incapable  of  cry  ftallifing.  Strong 
nitrous  acid  corrodes  and  dephlogifticates  a  con- 
fiderable  quantity  of  iron,  which  falls  to  the  bot 
tom. 

Marine  acid  likewife  diflolves  iron,  and  this  foluli- 
on  is  alfo  incryftallifable. 

The  Pruffian  acid  precipitates  iron  from  its  foluti- 
ons  in  tlie  form  of  Pruffian  blue. 

f  his  metal  is  likewife  fenfibly  acted  upon  by  alka 
line  and  neutral  liquors,  and  corroded  even  by 
thofe  which  have  no  perceptible  faline  impregna 
tion  ;  the  oils  themfelves,  with  which  iron  uten- 
fils  are  ufually  rubbed  to  prevent  their  rutting, 
often  promote  this  effect  in  fome  meafure,  unleis 
the  oils  have  been  previoufly  boiled  with  litharge 
or  calces  of  lead. 

Galls,  and  other  aftringent  vegetables,  precipitate 
iron  from  its  folutions,  of  a  deep  blue  or  puiple 
colour,  of  fo  intenfe  a  (hade  as  to  appear  black. 
It  is  owing  to  this  property  of  iron  that  the  cora- 
inon  writing  ink  is  made.  The  infufion  of  galls, 
and  alfo  the  Pruffian  alkali,  are  tefts  of  the  pre- 
fence  of  iron  by  the  colours  they  produce  on  any 
fluid.  Acids,  however,  diflblve  the  coloured  pre 
cipitates  by  the  former;  and  hence  it  arifes  that 
the  marine  acid  is  fuccefsfully  applied  to  take  off 
ink'fpots  and  iron  ftains  from  white  linens.  Al 
kalis,  however,  convert  thefe  iron  precipitates  in 
to  a  brown  ochre. 

Iron  rm  a  Crong  affinity  with  fulphur.  If  a  bar 
of  iron  be  ftrongly  ignited,  and  a  roll  of  brim- 
ftone  be  applied  to  the  heated  end,  it  will  com 
bine  with  the  iron,  and  form  a  fuiible  rnaf?,  which 
will  drop  dowa.  A'veflel  of  water  ought  to  be 
placed  beneath  for  the  purpofe  of  receiving  and 
extinguishing  it,  as  the  fumes  would  otherwife  be 
very  inconvenient  to  the  operator. 

A  mixture  of  iron-filings  and  fulphur  in  powder, 

moiftened 


C    239    3 

moiftened  with  water,  and  prefTed  fo  as  to  form 
a  pafte,  will  in  a  few  hours  fwell,  become  hot, 
fame,  and  even  burft  into  a  flame,  if  the  quan 
tity  is  large.  The  refiduum  furnifhes  martial 
vitriol.  This  procefs  is  fimilar  to  the  decompofi- 
tion  of  martial  pyrites  ;  from  which  fome  philo- 
fophers  account  for  hot  fpring-waters  and  fubter- 
raneous  fires.  The  mixture  of  water  in.  this  pafte 
feems  to  be  neceflary  to  enable  the  vitriolic  acid  of 
the  fulphur  to  act  on  the  iron. 

For  other  chemical  properties  of  this  metal,  fee 
CHEMISTRY-//;^*;  ;  for  its  electrical  and  mag 
netic  properties,  fee  ELECTRICITY  and  MAGNE 
TISM.  For  a  more  particular  account  of  its  na 
ture  and  ufes,  and  the  methods  of  making  and 
manufacturing  it,  fee  the  articles  IRON  and 
STEEL  ;  alfo  METALLURGY,  Part  II.  feet.  vii.  and 
Part  III.  feel.  v. 

Order  III.  SEMIMETALS. 

It  Bifmuth  j  tln-glafs.     Vifmutumt  Bifmutum,  Marcq/ita 
ofjicmalis*     It  is, 

a.  Of  a  whitifh  yellow  colour. 

b.  Of  a  laminated  texture,  foft  under  the  ham- 
mer,  and  neverthelefs  very  brittle. 

c.  It  is  very  fufible  ;  calcines  and  fcorifies  like 
lead,  if  not    rather    eafier :    and  therefore  it 
works  oa  the  cuppel.     It  is  pretty  volatile  in 
the  fire. 

t/.  Its  glafs  or  flag  becomes  yellowifh  brown,  and 
has  the  quality  of  retaining  foroe  part  of  the 
gold,  if  that  metal  Has  been  melted,  calcined, 
and  vitrified  with  it. 

e.  It  may  be  mixed  with  the  other  metals,  ex 
cept  cobalt  and  zinc,  making  them  white  and 
brittle. 

/,  It  diiiblves  in  aqua-fortis,  without  imparting  to 

it 


C     24°     II 

it  any  colour ;  but  to  the  aqua-regia  It  gives 
a  red  colour,  and  may  be  precipitated  out  of 
both  thefe  folutions  with  pure  water  into  a 
whice  powder,  which  is  called  Spanl/b  white. 
It  is  alfo  precipitated  by  the  acid  of  fea-falt ; 
which  laft  unites  with  it,  and  makes  the  •vifmu- 
tnm  corneum. 

g.  It  amalgamates  eafily  with  quickfilver.  Other 
metals  are  fo  far  attenuated  by  the  bifmuth, 
when  mixed  with  it,  as  to  be  ftrained  or  forced 
along  with  the  quickfilver  through  {kins  or 
leather. 

Bifmuth  is  found  in  the  earth. 

A.  Native.     This  refembles  a  regulus  of  bifmutb, 
but  confifts  of  fmallerfcales  or  plates. 

1.  Superficial,  or  in  crufts. 

2.  Solid,  and  compofed  of  finall  cubes. 
J5.  In  form  of  calx. 

I.  Powdery  or  friable  \  Odn-a  v/fmuti  This  fs- 
of  a  whitiih  yellow  colour';  it  is  found  in 
form  of  an  efHorefcence. 

It  has  b?-;n  cuftomary  to  give  the  name  of 
faivers  of  bfauth  to  the  pale  red  calx  of  co 
balt,  but  it  is  wrong;  becaufe  neither  the. 
calx  of  bid  :  ;  h,  nor  its  folutions,  become 
red,  this  being  a  quality  belonging  to  the 
cobalt. 

C.  Mineralifed  bifmuth.  This  is,  with  refpedt  to 
colour  and  appearance,  like  the  coarf;  teflela- 
ted  potter's  lead  ore  ;  but  it  confifts  of  very 
thin  fquare  plates  or  flakes,  from  which  it  re 
ceives  a  radiated  appearance  when  broken  crofs- 
wife. 

1.  Withfulphur. 

a.  With  large  plates  or  flakes. 
I.  With  fine  or  fmall  fcales. 

2.  With  fulphuratsd  iron. 

a.  Of 


r  *4'  i 

a.  Of  coarfe  wedge-like  fcales. 

This  miueralifed  bifmuth  ore  yields  a  fine 
radiated  regulus ;  for  which  reafon  it  has  been 
ranked  among  the  antimonial  ores  by  thofe 
who  have  not  taken  proper  care  to  melt  a  pure 
regulus  ore  deftitute  oi'  fulphur  from  it ; 
while  others,  who  make  no  difference  between 
regulus  and  pure  metals,  have  {till  more  po- 
iitively  aflerted  it  to  be  only  an  antimonial 
ore. 

.  With  fulphur  and  arfenic. 
a.  Of  a  whitifh  yellow  or  afti  colour.  It  has 
a  (hilling  appearance  j  and  is  compofed  of 
fmall  fcales  or  plates,  intermixed  very  fmall 
yellow  flakes  :  It  is  of  a  hard  and  folid  tex 
ture  :  Sometimes  ftrikes  fire  with  hard 
fteel :  Has  a  difagreeable  fmell  when  rub 
bed  :  Does  not  effervefce  with  aqua-fortis ; 
but  is  partially  diifolved  by  the  fame  acid 
(z). 

I.  Grey,  of  a  ftriated  form ;  found  at  Helfmg- 
land  in  Sweden,  and  at  Annaberg  in  Saxony. 
c.  With  variegated  colours  of  red,  blue,  and 
yellow  grey ;  found  at  Schneeberg  in  Sax 
ony. 

J.  With  green  fibres  like  an  amianthus  ;  at  Mif- 
nia  in  Germany,  and  at  Gillebeck  in  Nor 
way. 

e.  With  yellow  red  fhining  particles,  called 
mines  de  bifmuth  "Threes  in  French,  at  Geor- 
genftadt  in  Get  many,  and  at  Annaberg  in 
Saxony. 

/.  The 


(z)  This  folution,  being  diluted  with  water,  becomes 
a  kind  of  fympathetic  ii.-k ;  as  the  words  written  r/ith 
it  on  white  paper,  and  dried,  are  not  diftinguiflid  by 
by  the  eye ;  but  on  being  heated  before  the  lire, 
thrv  aiTunic  a  ycllowifh  colour. 


C    *4*    ] 

f.  The  minera  lifmuthi  arenacea,  mentioned  by 
Wallerius  and  Bomare,  belongs  alfo  to  the 
fame  kind  of  the  arfenicated  ores. 
4.  By  vitriolic  acid.     This  ore  is  called  wifmuth 
bluth  by  the  Germans.     It  is  faid  to  be  of  a  yel- 
lowifn,  reddifh,  or  variegated  colour ;  and  to 
be  found  mixed  with  the  calx  of  bifmuth,  in- 
crufting other  ores.     Kirwan,  p.  334. 
Ufa,  &c.  of  Bifmuth.     See   the  article  BISMUTH. 
Alfo  CHEMISTRY-/W^JC  /  and  METALLURGY,  Part 
II.  fed.  x.  and  Part  III.  fed.  viii. 
II.  Zinc  ;  fpeltre.     Zincum. 

a.  Its  colour  comes  neareft  to  that  oflead,  but  it 

does  not  fo  eafily  tarnifh. 

1.  It  Giows  a  texture  when  it  is  broken,   as  if  it 
were  compounded  of  flat  pyramids  (A). 

c.  Its  fpecific   gravity  to   water   is  as  6,900  or 
7000  to  1000. 

d.  It  melts  in  the  fire  before  it  has  acquired  a 
glowing  heat ;    but  when  it  has    gained  that 
degree  of  heat,  it  burns  with    a    flame  of  a 
changeable  colour,  between  blue  and  yellow. 
If  in  an  open  fire,  the  calx  rifes  in  form  of 
foft  white  flowers  j  but  if  in  a  covered  vefiel, 
with  the  addition   of  feme  inflammable,  it  is 
di (tilled  in  a  metallic  form  :  in  which  opera 
tion,  however,  part  of  it  is  fcmetimes  found 
•vitrified. 


(A)  It  cannot  de  reduced  into  powder  under  the 
hammer  like  other  femimetals.  When  it  is  wanted 
very  much  divided,  it  muft  be  granulated,  by  pouring 
it  while  fufcd  into  ccld  water;  or  filed,  which  is  very 
tedious,  as  it  fluffs  and  fills  the  teeth  of  the  file.  But 
if  heated  the  mod  poflible  without  fufingit,  Macquer 
afferts,  that  it  becomes  ib  brittle  as  to  be  pulverifcd  in 
a  mortar. 


[     243     ] 

e.  It  unites  with  all  the  metals  (a)  except  bif- 
muth  and  nickel,  and  makes  them  volatile. 
It  is,  however,  not  eafy  to  unite  it  with 
iron  without  the  addition  offulphur.  It  has 
the  ftrongeft  attraction  to  gold  and  copper, 
and  this  laft  metal  acquires  a  yellow  colour 
by  it ;  which  has  occasioned  many  experi 
ments  to  be  made  to  produce  new  metallic 
compofitions. 

/.  It  is  diilblved  by  all  the  acids  :  of  thzfe  the 
vitriolic  acid  has  the  ftrongeft  attraction  to  it ; 
yet  it  does  not  diflblve  it,  if  it  is  not  previoufly 
diluted  with  much  water. 

g.  Quickfilver  amalgamates  eafierwidi  zinc  than 
with  copper  ;  by  which  means  it   is  feparated 
from  competitions  made  with  copper. 
b.  It  ieems  to  become  electrical  by  iriclicn. 
Zinc  is  found,  . 

A.  Native. 

Zinc  has  been  met  with  native,  though  rarely, 
in  the  form  of  thin  and  flexible  filaments, 
of  a  grey  colour,  which  were  eafily  iiiflarnc-d 
when  applied  to  a  fire.  And  Bomare  affirms 
that  he  has  feen  many  fm ill  pieces  of  native 

zinq 


(B)  It  brightens  the  colour  of  iron  almofl  into  a  fil- 
ver  hue  ;  changes  that  of  copper  to  a  yellow  or  gold 
colour,  but  greatly  dcbafes  the  colour  of  gold  and  de- 
ftroys  its  malleability.  It  improves  the  colour  and  luftre 
of  lead  and  tin,  rendering  them  firmer,  and  confe- 
quently  fitter  for  fundry  mechanic  ufes.  Lead  will 
bear  an  equal  weight  of  zinc,  without  lofing  too  much 
of  its  malleability. — The  procefs  for  giving  the  yellow 
colour  to  copper,  by  the  mixture  of  zinc,  and  of  its 
ore  called  calamine,  has  been  defcribed  above  under 
the  Ufes  of  Copper. 

Y 


C 

zinc  among  the  calamine-mines  in  the  duchy 
of  Limbourg  and  in  the  zinc-mines    at  Go- 
flar,  where  this  femimetal    was    always    fur- 
rounded  by  a  kind  of  ferruginous  yellow  earth, 
or  ochraceous  fubftances.     See  the  detached 
article  ZINC. 
B.  In  form  of  calx, 
(i.)  Pure. 

a.  Indurated. 

1.  Solid. 

2.  CryRallifed. 

This  is  of  a  whitifh-grey  colour,  and 
its  external  appearance  is  like  that  of  a 
lead  fpar  ;  it  cannot  be  described,  but 
is  eafily  known  by  an  experienced  eye. 
— It  looks  very  like  an  artificial  glafs 
of  zinc  ;  and  is  found  among  other  cala- 
mines  at  Namur  and  in  England. 
(2.)  Mixed. 

A.  With  a  martial  ochre. 

i.      Half    indurated.      Calamine;     Lapis 
calamlnaris. 

a.  Whitilh  yellow, 

b.  Reddifh  brown.     This  feems  to  be  a 
mouldered  or  weathered  blende. 

B.  With  a  martial  clay  or  bole, 
c.  With  a  lead  ochre  and  iron. 

D.  With  quartz  :  Zeolite  of  Friburgh.    ' 

The  real  contents  of  this  fubttance  were 
firft  difcovered  by  M.  Pelletier.  It  was 
long  taken  for  a  true  zeolite,  being  of 
a  pearl  colour,  cryftallifed,  and  femitran- 
fparent.  It  confifts  of  laminae,  diverging 
from  different  centres,  and  becoming  ge 
latinous  with  acids.  Its  contents  are  48 
to  52  per  cent,  of  quartz,  36  of  calx  of 
zinc,  and  8  or  12  of  water.  (Juroww, 
p.  318.) 

C.  Mine- 


C    245    ] 

C.  Mineralifed. 

(i.)  With  fulphurated  iron.  Blende,  mock- 
lead,  black-jack,  mock-ore;  pfeudogalena  and 
blende  of  the  Germans. 

A.  Mineralifed  zinc  in  a  metallic  form.  Zinc 
ore.  This  is  of  a  metallic  bluifh-grey 
colour,  neither  perfectly  clear  as  a  pot 
ter's  ore,  nor  fo  dark  as  the  Swedifh  iron 
ores. 

1.  Of  a  fine  cubical  or  fcaly  texture. 

2.  Steel-grained. 

E.  In  form  of  calx.  Blende.  Mock-lead ; 
Sterile  nigrum.  Pfiudo-galenz  (c.)  This  is 

found, 
I .  Wi  th  c  oti  rfe  fc  al  e  s. 

a.  Yellow ;  femi  tranfparent, 

£.  Greenifh. 

c.  Greenifh-black  ;  peclblendst   or  fitch 

Iknde  of  the  Germans. 
{/.  Blackiih -brown. 
2.  With  fine  fcales, 

a.  White. 

b.  Whitifh-yellow, 

c.  Reddifh-brown. 

3.  Fine  and  fparkling  ;  at  Gofbr  called  Iraun 
blyeriz.     Its  texture    is    generally  fcaly  ; 
ibmetimescryftallifed  and  femitranfparent. 

y  2  it. 


(c)  The  varieties  of  pfeudo-galena,  or  black-jack,. 
are  in  general  of  a  lamellar  or  Icaly  texture,  and  fre 
quently  of  a  quadrangular  form,  refembling  galena, 
They  all  lofe  much  of  their  weight  when  heated,  and 
burn  with  a  blue  flame  ;  but  their  ipecific  gravity  is  con- 
fiderably  inferior  to  that  of  true  galena.  Almoll  all 
contain  in  mixture  of  lead-ore.  Moft  of  them  exhale  a 
fulphureous  fmell  when  fcraped,  or  at  leaft  when  vitri> 
olic  or  marine  acid  is  dropped  on  then:. 


It  gives  fire  with  fteel ;  but  docs  not  de 
crepitate,  nor  fmoke  when  heated  :  yet  it 
lofes  about  1 3  per  cent,  of  its  weight  by 
torrefaclion. 

a.  Dark-brown. 

b.  Red,  which    becomes   phofphorefcent 
when  rubbed  ;   found  at  Scharfenberg 
in  Mifnia.      (  Brnnich  ) . 

.  £.  Greenilh,  yellowifli-greep.,  or  red.  It 
has  different  degrees  of  tranfparency, 
and  is  fometimes  quite  opaque.  When 
fcraped  with  a  knife  in  the  dark,  it  emits 
light,  even  in  water;  and  after  under 
going  a  white  heat,  if  it  is  diftilled^r 
ft,  a  dliceous  fublirnate  rifes,  which 
ihows  it  contains  the  fpai  ry  acid,  pro 
bably  ur.iud  to  the  metal,  imce  it  iub- 
limes. 

4.  Of  a  metallic  appearance ;  glanz  llcnds. 

This  is  of  a  bluifh-grey,  of  a  fcaly  or 
fleel-grained  texture,  and  its  fc;rm  gene 
rally  cubical  or  rhomboidal.  It  lofes 
nearly  one  flxth  of  its  weight  by  calcina- 
nation  ;  and  after  calcination  it  is  more  fo- 
luble  in  the  mineral  acids. 

ico  parts  of  this  ore  afforded  to  Berg 
man  about  52  of  zinc,  8  of  iron,  4  of 
copper,  26  of  fulphur,  6  of  filex,  and  4  of 
water. 

5.  Cryflalline. 

a.  Dark-red,  very  fcarce ;  found  in  a 
mine  near  Freyberg.  Something  like 
it  is  found  at  the  Morgenftern  and 
Himmelsfufte. 

I.  Brown.     In  Hungary  and  Tranfylva- 

T('TL. 

c.  Black.     Hungary. 

Thefe 


[     247     J 

Thefe  varieties  may  eafily  be  mifhi- 
ken  for  rock  cryftals  ;  but  by  expert- 
eiice  they  may  be  difttnguifhed  on  ac 
count  of  their  lamellated  texture  and 
greater  foftnefs.  Their  tranfparency 
arifes  from  a  very  fmall  portion  of  iron 
in  them. 
(2.)  Zinc  mineralifed  by  the  vitriolic  acid. 

This  ore  has  been  already  defcribed  among 
the  middle  Salt*,  at  Vitriol  of  zinc.- 
Ufes,  &c.  of  zinc.     See  the  detached  article  ZINC  ;. 
Alfo   CHEMISTRY-/-?^;  aod  METALLURGY, 
Part  II.  feet  xii.  and  Part  III.  under  feel.  iii. 

III.  Antimony ;  Anlimomum  Stibium.     This  femime- 
tal  is, 

a,  Of  a  white  colour  almofl  like  filver. 

b.  Brittle  ;  and  in  regard  to  its  texture,  it  coruiftj 
of  finning  planes  of  greater  length  than  breadth. 

c.  In  the  Ere  it  is  volatile,  and  volatilifes  part  of 
the  other  metals  along  with  it,  except  gold  and 
platina.     It  may,  however,  in   a  moderate  fire, 
be  calcined  into  a  light-grey  calx,  which  is  pretty 
refractory  in  the'  fire ;  but  meks  at  la-ft  to  a  glafs, 
of  a  reddiih-brown  colour.. 

d.  It  di Halves  in  fpirit  of  fea-falt  and  aqua-regia, 
but   is   only  corroded  by  the  ipirit  of  nitre  into- 
n  white  cab: ;  it  is  precipitated  out  of  the  aqna.- 
regia  by  watsr* 

e.  It  has  an  emetic  quality  when  its  calx,  glaf?,.  <  7 
metal,  is  diffrlved  in  an.  acid,  except  when  in  thi 
fpirit  of  nitre,  which  has  nc>t  this  eiTeol:. 

f.  It  amalgamates  with  q.uickfilver,  if  the  reguluc,, 
when  fuied,  is  put  to  it ;  but  the  quiekfilver  ought, 
for  this  purpofe  to  be  covered  with  w,irm  water  ; 
it  amalgamates  with  it  likewife,  if  the  regulus  c,f 
antimony  be  previoufly  melted  with  an  addition* 

Y  3,  Antuacnjr 


C    248    ] 

Antimony  is  found  in  the  earth. 
A.  Native.      Regulus  antlmoniinai'wus. 

This  is  of  a  filver  colour,  and  its  texture  is 
compofed  of  pretty  large  {Lining  planes. 

This  kind  was  found  in  Carls  Ort,  in  the 
mine  of  Salberg,  about  the  end  of  the  laft  cen 
tury  ;  and  fpecimens  thereof  have  been  prefer- 
ved  in  collections  under  the  name  of  an  arienical 
pyrites,  until  the  mine-m after  Mr  Von  Swab  dif- 
covered  its  real  nature,  in  a  treatile  he  communi 
cated  to  the  Royal  Academy  of  Sciences  at 
Stockholm  in  the  year  1748.  Among  other  re 
markable  obfervationa  in  this  treatife,  it  is  faid, 
firft,  That  this  native  antimony  eafily  amalga 
mated  with  quickfilver  ;  doubtlefs,  becaufe  it  was 
imbedded  in  limeftone  ;  fince,  according  to  Mr 
Pott's  experiments,  an  artificial  regulus  of  anti 
mony  may,  by  means  of  lime,  be  difpofed  to  an 
amalgamation  :  Secondly,  That  when  brought 
in  form  of  a  calx,  is  (hot  into  cryftals  during  the 
cooling. 

JB,  Mineralifed  antimony. 
(i)Withfulphur. 

This  is    commonly  of  a  radiated  texture, 

compofed  of  long  wedge-like  flakes  or  plates  ; 
-  it  is  nearly  of  a  lead-colour,  and  rough  to  the 

touch. 

a.  Of  coarfe  fibres. 

b.  Of  fmall  fibres. 

<7.  Steel-grained,  from  Saxony  and  Hungary. 
<?.  Cryftallifed,  from  Hungary. 

I.  Of  prifmatical,  or  of  a  pointed  pyrami 
dal  figure,  in  which  laft  circumftance  the 
points  are  concentrical. 

Cronftedt  mentions  a  fpecimen  of  this,. 
in  which  the  cryftals  were  covered  with 
very  minute  cryftals  or  quartz,  except  at 
the  extremities,  where  there  was  always 

a  little 


t    249    3 

a  little  hole :  this  fpecimen  was  given  for 
afosferri  fpar. 

(2.)  With  fulphur  and  arfenic.     Red  antimony 
ore  ;  Antimonium  folare. 

This  is  of  a  red  colour,  and  has  the  fame 
texture  with  the  preceding,  though  its  fibres 
are  not  fo  coarfe. 

a.  With  fmall  fibres. 

b.  With  abrupt   broken  fibres,  from   Braunf- 
dorffin  Saxony,  and  from  Hungary. 

All  antimonial  ores  are  fomewhat  arfe- 
nical,  but  this  is  more  fo  than  the  preceding 
kinds. 
(3.)  With  fulphurated  filver.     Plumofe  filver- 

ore,  vrfederertz  of  the  Germans. 
(4.)  With  fulphurated  filver,  copper,  and  arfe 
nic  ;  the  dalfahl-ertz  of  the  Germans. 

With  iulphurated  lead ;  radiated  lead-ore. 
By  the  aerial  acid. 

This  ore  was  lately  difcovered  by  Mongez, 
among  thofe  of  native  antimony  from  the 
mine  of  Chalanc'es  in  Dauphiny.  It  confifts 
of  a  group  of  white  cryftallifed  filaments  of  a 
needle-form  appearance,  diverging  from  a  com 
mon  centre,  like  zeolite.  They  are  infoluble 
in  nitrous  acid ;  and,  on  being  urged  by  the 
flame  of  a  blow-pipe,  upon  apiece  of  charcoal, 
they  are  diffipated  into  white  fumes,  or  anti 
monial  flowers,  without  any  fmell  of  arfenic  ; 
from  whence  it  follows,  that  thefe  needle  form 
ed  cryftals  are  a  pure  calx  of  antimony,  form 
ed  by  its  combination  with,  or  mineralifed  by, 
the  aerial  acid.  See  Kirzuan,  p.  325,  and 
Journal de  Phyfique  for  July  1787,  p.  67. 
Iffes,  &c.  By  the  name  of  antimony  is  commonly 
underftood  the  crude  antimony  (which  is  com 
pounded  of  the  metallic  part  and  fulphur)  as  it  is 

melted 


J.1K 

It} 


£     «5o    J 

melted  out  of  the  ore  ;  and  by  the  name  of  regu 
lus,  the  pure  femimetal. 

r.  Though  the  regulus  of  antimony  is  a  metallic 
fubftance,  of  a  confiderably  bright  white  colour,, 
and  has  the  fplendor,  opacity,  and  g:  ivity  of  a 
metal,  yet  it  is  quite  unmalieable,  ana  falls  into 
powder  initead  of  yielding  c»r  expand"  i  r  uuder 
the  hammer  ;  on  \vhich  account;  it  is  clalled  among 
the  femimet.ils. 

2.  Regulus  of  antimony  is  ufed  in  various  metallic 
mixtures,  as    [or  pr.nting  types,  metallic  fpecu- 
lums,  &c.  and  it  enters  into  the  belt  fort  of  pew 
ter  ware. 

3.  It  mixes  with,  and  diflblves  various  metals  5  in 
particular  it  affects  iron  the  moft  powerfully  ;  and 
what  is  very  remarkable,  when  mixed  together, 
the  iron  is  prevented  from  being  attracted  by  the 
load  (lone. 

4.  It  affects  copper  next,  then  tin,  lead,  and  filver; 
promoting  their  fufion,  and  rendering  them  all 
brittle  and  unmalleable  :  but  it  will  neither  unite 
with  gold  nor  mercury  ;  though  it  may  be  made 
to  combine  with  this  laft  by  the  interpolation  of 
fulphur.     In  this  cafe  it  refembles   the  common 
JEthiops,  and  is  thence  called  antimontal  JEth'iops. 

5.  Regulus  of  antimony  readily  unites  with  fulpbur 
and  forms  a  compound  of  a  very  faint  metallic 
fplendor :  it  afiuitfes  the  form  or  long  needles  ad 
hering  together  laterally  :  it  ufually  formed  na 
turally  alfo  in   this  fhape.     This  is  called  cruJs 
antimony. 

6.  But  though  antimony  has  a  confrderable  affinity 
to  fulpkur ;  yet  all  the  metals,  except  grid  and 
mercury,  have  a  greater    affinity   to  that  com 
pound.     If  therefore  iron,  copper,  lead,  filler, 
or  tin,  be  melted  with  antimony,  the  fulphur  will 
unite  with  the  metal,  an  j  be  fcparated-  from  the 

regulus* 


[       25'       1 

re^ulus,  which,  however,  takes  up  fome  part  of 
the  metal,  for  which  reafon  it  is  called  martial re- 
gufuSf  regiAus  veneris,  &c. 

7.  When  gold  is  mixed,  or  debafed  by  the  mixture 
of  other  metals,  it  may  be  fufed  wirh  antimony  j 
for  the  fulphur  combines  with   the  bafe   metals, 
which,    being  the    lighter,  rife  up  into   fcoria, 
while  the  regulus  remains  united  at  the  bottom 
with  the  gold  ;  which  being  urged  by  a  (Ironger 
degree  of  heat,  is  freed  from  the  femimetal,  which 
is  very  volatile.     This  method  of  refining  gold  is 
the  eafieft  of  all. 

8.  But  the  moft  numerous  purpofes  to  which  this 
metal  has  been  applied  are  thofe  of  the  chemical 
and  pharmaceutical  preparations.     Lemery,  in 
bis  Treat ife  on  Antimony,  dffcribes  no  lefs  than 
2CO  procefTes  and  formulas;  among  which  there 
are  many  good  and  many  ufelefs  ones.     The  fol 
lowing  deferve  to  be  mentioned  on  account  of  their 
utility. 

9.  Antimony  melts  as  foon  as  it  is  moderately  red 
hot,  but  cannot  fuftain  a  violent  degree  of  fire, 
as  it  is  thereby  diffipaced  into  fmoke  and  white  va 
pours,  which  adhere  to  fuch  cold  bodies  as  they 
meet  with,  and  are  collected  into  a  kind  of  fariua 
or  powder,  called  Jiowers  of  antimony, 

jo.  If  it  be  only  moderately  heated,  in  very  fm all 
pieces,  fo  as  not  to  melt,  it  becomes  calcined  in 
to  a  greyifh  powder  deftitute  of  all  fplendor,  cal 
led  calx  cf  antimony .  This  calx  is  capable  of  en 
during  the  moft  violent  fire  ;  but  at  latl  it  will  run 
into  a  glafs  of  a  reddifh-yellow  colour,  fimilar  to 
that  of  the  hyacinth.  The  infufion  made  of  this 
coloured  antimonial  glafs,  in  acidulous  wine  (fuch 
ris  that  of  Bourdeaux)  for, the  fpaoe  of  5  or  6 
hours,  is  a  very  violent  emetic. 

ii.  If  equal  parts  of  nitre  and  regulus  of  antimony 
be  de-flaunted  over  tho  fi'-e,  the  grey  calx  which 
remains  is  called  liver  of  antimony. 

12.    If 


1 2.  If  regulus  of  antimony  be  melted  with  two  parts 
of  fixed  alkali,  a  mafs  of  a  reddifli-yellow  colour 
is  produced,  which  being  diflblved  in  water,  and 
any  acid  being  afterwards  added,  a  precipitate  is 
formed  of  the  fame  colour,  called  golden  Julphur  of 
antimony. 

13.  Fixed  nitre,  viz.  the  alkaline  fait  that  remains 
after  the  deflagration  of  nitre,  being  boiled  with 
fmall  pieces  of  regulus  of  antimony,  the  folution 
becomes  reddifh ;  and,  on  cooling,  depoOts  the 
antimony  in  the  form  of  a  red  powder,  called  mi 
neral  kermes. 

14.  Equal  parts  of  the  glafs,  and  of  the  liver  of  an 
timony,  wellpulverifed  and  mixed  with  an  equal 
quantity  of  pulverifed  cream  of  tartar,  being  put 
mto  as  much  water  as  will  diflblve  the  cream  of 
tartar,  and  boiled  for  12  hours,  adding  now  and 
then  fome  hot  water  to  replace  what  is  evapora 
ted,  the  whole  is  to  be  filtered  while  hot ;  then 
being  evaporated  to  drynefs,  the  faline  matter 
that  remains  is  the  emetic  tartar. 

15.  The  regulus  of  antimony  being  pulverifed,  and 
diftilled  with  corrofive  fublimate  of  mercury,  a 
thick  white  matter    is  produced,    which   is  ex 
tremely  corrofive ,  and  is  called  butter  of  antimony. 
This  thick  fubftance  may  be  rendered  limpid  and 
fluid  by  repeated  diftillations. 

1 6.  On  mixing  the  nitrous  acid  with  this  butter  of 
antimony,  a  kind  of  aqua  regia  is  diftilled,  call 
ed  bezoardic  fpirit  of  nitre. 

17.  The  white  matter  that  remains  from  this  lad 
diftillation  may  be  rediftilled  with  frefh  nitrous 
acid  ;  and  the  remainder  being  waftied  with  wa 
ter,  is  called  be%oar  mineral,  which  is  neither  fo 
volatile  nor  fo  cauftic  as  the  antimonial  butter. 
This  butter  being  mixed  with  water,  a  precipi 
tate  falls  to  the  bottom,  which  is  very  improper 
ly  called  mereurius  vite,  for  it  is  in  fa&  a  very  vi 
olent  emetic. 

1 8.  But 


C    *53    D 

1 8.  But  if,  inftead  of  the  regulus,  crude  antimony 
be  employed,  and  the  fame  operation  be  perfor 
med,  the  regulinepartfeparates  from  the  fulphur, 
unites  to  the  mercury,  and  produces  the  fubftance 
which  is  called  cinnabar  of  antimony. 

19.  Crude  antimony  being  projected  in  a  crucible, 
in  which  an  equal  quantity  of  nitre  is  fufed,  deto 
nates  ;  is  calcined,  and  forms  a  compound  called 
by  the  French  fondant  de  Retrou,  or  antlmoine  di« 
aphoretique  non  lave.     This  being  diffolved  in  hot 
water,  falls  to  the  bottom  after  it  is  cold ;  and 
after  decantation  is  known,    when  dry,  by  the 
name  of  diaphoretic  antimony.     This  preparation 
excites  animal  perfpiration,  and  is  a  good  fudori- 
fic.     ^The  fame  preparation  may  be  more  expedi- 
tioufly  made  by  one  part  of  antimony  with  two 
and  a  half  of  nitre,  mixed  together  and  deflagra 
ted  :  the  refidue  of  which  is  the  mere  calx  of  an 
timony,  void  of  all  emetic  power. 

20.  And  if  the  detonation  be  performed  in  a  tubu 
lated  retort,  having  a  large  receiver,  containing 
fome  water  adapted  to  it,  both  a  clyffus  of  anti 
mony  and  the  antimonial  flowers  rnay  be  oblain- 
edat  the  fame  time,  as  Neumann  afierts. 

2 1 .  When  nitre  is  deflagrated  with  antimony  over 
the  fire,  the  alkaline  bafis  of  the  nitre  unites  with 
the  calx  of  the  femimetal,  which  may  be  fepara- 
ted  by  an  acid,  and  is  called  materia perlata.     See 
farther  the  article  ANTIMONY  ;  alfo  METALLUR 
GY,  Part  II.  fe6t  ix. 

IV.  Arfenic.     In  its  metallic  form,  is, 

a.  Nearly  of  the  fame  colour  as  lead,  but  brittle, 

and  changes  fooner  its  fKining  colour  in  the  air, 

firft  to  yellow,  and  afterwards  to  black. 
I.  It  appears  laminated  in  its  fractures,  or  where 

broken. 
c.  Is  very  volatile  in  the  fire,  burns  with  a  fmall 

flame,  and  gives  a   very,  difagreeable  fmell  like 

garlic. 

t 


C     254    ] 

<L  It  is,  by  reafon  of  its  volatility,  very  difficult 
t^  be  reduced,  unlefs  ft  is  mixed  with  other  me 
tals  :  However,  a  regulus  may  be  got  from  the 
•white  arfenic,  if  it  is  quickly  melted  with  equal 
r.  arts  of  pot  allies  andfoap;  but  this  regulus  con 
tains  generally  fome  cobalt,  mod  of  the  white 
arfenic  being  produced  from  the  cobalt  ores  du 
ring  their  calcination.  The  white  arfenic,  mix 
ed  with  a  phlogifton,  fublim^s  likewife  into  cc*lo- 
edral  cryitals  of  a  metallic  appearance,  whofe  fpe- 
cific  gravity  is  8,308. 

t.  The  calx  of  arfenic,  which  always,  on  account  of 

its  volatility,  muft  be  got    as  a  fublimation,  is 

white,  and  eafily  melts  to  a  glafs,  whole  fpecific 

gravity  is  5,000.     When  fulphur  is  blended  in 

^  this  calx,  it  becomes  of  a  yellow,  orange,  or  red 

•^•colour;  and  according  to  the  degrees  of  colour 

•  is  called  orpiment  or  yellow  arfenic  ;  fandarach,  re- 
a/gar,  or  red  arfenic  ;  and  alfo  rubinus  arfenlci. 

f.  This  calx  and  glafs  are  diflbluble  in  water,  and 
in  all  liquids  ;  though  not  in  all  with  the  fame 
facility.     In  this  circumltance  arfenic  refembles 
the  falts  ;  for  which  reafcn  it  alfo  might  be  rank 
ed  in  that  clafs. 

g.  The  regulus  of  arfenic  diffolves  in  fpirit  of  nitre; 
but  as  it  is  very  difficult  to  have  it  perfectly  free 
from  other  metals,  it  is  yet  very  little  examined 
in  various  menftrua. 

h.  It  is  poifonous,  efpecially  in  form  of  a  pure 
calx  or  glafs :  But  probably  it  is  lefs  dangerous 
when  mixed  with  fulphur,  iince  it  is  proved  by 
experience,  that  the  men  at  mineral  works  are 
not  fo  much  affected  by  the  fmoke  of  this  mix 
ture  as  by  the  fmoke  of  lead,  and  that  fome  na 
tions  make  ufs  of  the  red  arfenic  in  fmall  dofes 
as  a  medicine. 

i.  It  unites  with  all  metals,  and  is  likewife  much 
ufed  by  nature  itfe.lf  to  diffoive,  or,  as  we  term 
it,  to  minera/ifc,  the  metals,  to  which  its  vola 
tile 


[     »J5     3 

tility  and  diftblubility  in  water  mud  greatly  con 
tribute.  It  is  likewife  moft  generally  mixed  with 
fulphur. 

k.  It  abforbs  or  expels  the  phlogiflon,  which  has  co 
loured  glafTes,  if  mixed  with  them  in  the  fire. 

Arfenic  is  found, 

[t.]  Native;    called  Scherbencoboh    and  FKegenflein 
by  the  Germans. 

It  is  of  a  lead  colour  when  frefh  broken,  and 
may  be  cut  with  a  knife,  like  black  lead,  butfooti 
blackens  in  the  air.  It  burns  with  a  fznall  flame, 
and  goes  off  in  fmoke. 

A.  Solid  and  teftaceous ;  Scherbencoboh. 

B.  Scaly. 

C.  Friable  and  porous ;  Fllegenftein. 
(  i.)  With  fhining  mTures. 

This  is  by  fome  called  Spigel  cobalt. 
[2.3   In  form  of  a  calx. 

A.  Pure,  or  free  from  heterogeneous  fubftances. 

1.  Loofe  or  powdery. 

2.  Indurated,  or  hardened.     This  is  found  in 
form  of  white  femi-tranfparent  cry  Hals. 

B.  Mixed. 

A.  With  fulphur. 
i.  Hardened. 

a.  Yellow.     Orpiment ;  Auripigmentnm. 

b.  Red.     Native  realgar,  or  fandarach. 
B.  With  the  calx  of  tin,  in  the  tin-grains. 

c.  With  fulphur  and  filver;  in  the  rotkguldcn 
or  red  filver  ore. 

D.  With  calx  of  lead,  in  the  lead-fpar. 

E.  With  calx  of  cobalt,  in  the  efflorefcence 
of  cobalt. 

[3.]  Mineralifed. 

A.  With  fulphur  and  iron.  Arfenical  pyrites 
or  marcafite.  Thefe  kinds  in  Cornwall  are 
called  Jilvsry  or  white  mundics  and  plate  mun- 
dies. 

7,  This 


This  alone  produces  red  arfenic  when  calci 
ned.  It  is  of  a  deeper  colour  than  the  follow 
ing. 

£.  With  iron  only.  This  differs  with  regard  to 
its  particles  ;  being, 

1.  Steel-grained. 

2.  Coarfe-grained. 

3.  Cryftallifed. 

a.  In  an  oclcedral  figure.     This  is  the  moft 
common  kind. 

b.  Prifmatical.     The  fulphureous  marcafite 
is  added  to  this  kind  when  red  arfenic  is 
to  be  made  ;  but  in  Sweden  it  is  fcarcer 
than  the  fulphureous  arfenical  pyrites. 

C.  With  cobalt,  almoft  in  all  cobalt  ores. 

D.  With  filver.          ">  c  ,       0.. 

E.  With  copper.         [  See  "ncler.  ***"• 

F.  With  antimony.  j      and  Antl™«^ 

For  the  Ufes  of  Arfemc,  fee  the  detached  article 
ARSENIC,  and  CHEMISTRY  -Index ;  alfo  ME 
TALLURGY,  Part  II.  fecr.  xiii.  and  Part  III. 
feel:,  viii. 

V.  Cobalt. 

This  fernlmetal  is, 

a.  Of  a  whitifh  grey  colour,  nearly  as  fine-tern- 
pered  fteel. 

b.  Is  hard  and  brittle,  and  of  a  fine-grained  tex 
ture;  hence  it  is  of  aduiky,  or  not  fhining  ap 
pearance. 

c.  Itsfpecific  gravity  to  water  is  6000  to  1000. 

d.  It  is  fixed  in  the  fire,  and  becomes  black  by 
calcination  :  it  then  gives  to  glalfes  a  blue  co 
lour,  inclining  a  little  to  violet,  which  colour, 
of  all  others,  is  the  moft  fixed  in  fire. 

A  The  concentrated  oil  of  vitriol,  aquafortis,  and 
aqua-regia,  diffolve  it ;  and  the  folutiorts  become 
red.  The  cobalt  calx  is  likewife  diflblved  by 

the 


the -fame  menflrua,  and  alfo  by  the  volatile  al 
kali  and  the  ipirit  of  fea  fait. 

f.  When  united  with  the  calx  of  arferiic  in  a  flow 
(not  a  brifk)  calcining  heat,  it  aiiiimes  a  red 
colour  :  the  fame  colour  is  naturally  produced 
by  way  of  efflorefcence,  and  is  then  called  the 
lloom  orjlutvers  of  cobalt.     When  cobalt  and  ar- 
fenic  are  melted  together  in  an  open  fire,  they 
produce  a  blue  flame. 

g.  It  does  not  amalgamate  with  quickfilver  by  any 
means  hitherto  known. 

h.  Nor  does  it  mix  with  bifrrmth,  when  melted 

with  it,  without  addition  of  fome  medium  to 

promote  their  union. 

i.]  Native  cobalt.     Cobalt  "with  arfenic  and  iron 
in  a  metallic  form. 

Pure  native  cobalt  has  not  yet  been  found : 
that  which  pafles  fox  fuch,  according  to  Kirvvan, 
is  mineralifed  by  arfenic.  Bergman,  however,  in 
his  Sciagraphia,  has  entered  this  prefent  ore  un 
der  the  denomination  of  native  cobalt:  and  cer 
tain  it  is,  that  among  all  the  cobaltic  ores,  this 
is  the  neareft  to  the  native  ftate  of  this  femime- 
tal.  It  always  contains  a  fmall  quantity  of 
iron,  befides  the  arfenic,  by  which  it  is  minerali 
fed. 

This  is  of  a  dim  colour  when  broken,  and  not 
unlike  fteel.     It  is  found, 
c.  Steel -grained,  from  Loos  in  the  parifh  of  Fa- 

rila  in  the  province  of  Helfmgeland,  and  Schnee- 

berg  in  Saxony, 
1.  Fine-grained,  from  Laos. 

c.  Coarfe-grained. 

d.  Cryftallifed  : 

1.  In  a  denditrical  or  arborefcent  form  ; 

2.  Polyhedral,  with  (Lining  furfaces  ; 

3.  In  radiated  nodules. 

Z  2  [>]  Cal- 


[2  ]  Ciilciform  cobalt.     Cobalt  is  mod  commonly 
found  in  the  earth  mixed  with  iron. 
A.  In  form  of  a  calx. 

j.)  With'iron  without  arfenic. 

a.  jLooie  or  friable ;  cobalt  ochre.  This 
is  black,  and  refembles  the  artificial 
z  a  fire. 

l\  Indurated  :  Mlnera  colal.il  vtirea.  The 
fchlacken  or  flag  cobalt.  Th's  is  likewife 
of  a  black  colour,  but  of  a  gialTy  texture, 
and  feems  to  have  loft  that  i'ubftance  which 
rnineralifed  it,  by  being  decayed  or  wea 
thered. 

J.)  With  arfenical  acid;  cobalt-blut,  Germ. 
Ochra  cobahi  rulra  ;  bloom,  flowers,  or  efflo- 
refcence  of  cobalt. 

a.  Loofe  or  friable.     This  is  often  found  of 
a  red  colour  like  other  earths,  fpread  very 
thin  on  the  cobalt  ores ;  and  is,  when  of  a 
pale  colour,  erroneoufly  calhdfawers  of 
btfmnth. 

b.  Indurated.     This  is  commonly  cryftalli- 
fed  in  form  of  deep  red  femitranfparent 
rays  or  radiations  :  It  is  found  at  Schnee- 
berg  in  Saxony. 

jB.  Mineralifed. 

i.)  With  fulphurated  iron. 

This  ore  is  of  a  light  colour,  nearly  re- 
fembling  tin  or  filver.     It  is  found  cryftalli- 
fed  in  a  polygonal  form. 
a.  Of  a  flaggy  texture. 
I.  Coarfe-grained. 

This  ore  is  found  in  Baftnafgrufva  at 
Raddarfhyttan  in  Weftmanland,  and  difco- 
vers  not  the  leaft  mark  of  arfenic.  The 
coarfe-grained  becomes  ilimy  in  the  fire,  and 
iticks  to  the  ftirring  hook  during  the  calci 
nation  in  the  fame  manner  as  many  regules 

do: 


[     *S9     ] 

do  :  It  is  a  kind  of  regule  prepared  by  na 
ture.  Both  thefe  give  a  beautiful  colour. 
2.)  Withfulphur,  arlenic,  and  iron.  This  re- 
fembles  the  arfenicaved  cobalt  ore,  being  on 
ly  rather  of  a.  whiter  or  lighter  colour.  It 
is  found, 

a.  Coarfe-grained. 

b.  Cryftalliied; 

I.  In  a  polygonal  figure,  with  ftiining  fur- 
faces,  or  glanzkobolt.     It  is  partly  of  a 
white  or  light  colour,  and  partly  of  a 
fomewhat  reddiih  yellow. 
(3.)  With  fulphurate-d  and  arfenjcated  nickel 

and  iron  ;  fee  Kupfcr-nickel,  below. 
Ufes,  &c.   See  the  article  COBALT.  S?e  alfo  CHE- 
MISTRY-//W/WC/    and  METALLURGY,   Part  II. 
feel.  xi. 

VI.  Nickel ;  Nicolum.  This  is  the  lateft  difcovered 
femimetal.  It  was  firft  defcribed  by  its  difco- 
verer  Mr  Cronftedt,  .in  the  Ads  of  the  Royal 
Academy  of  Sciences  at  Stockholm  for  the  years 
1751  and  i  54,  where  it  is  faid  to  have  the  fol 
lowing  qualities : 

j.  It  is  of  a  white  colour,  which,  however,  in 
clines  fomewhai  to  red. 

2.  Of   a  folid  texture    and  fhining  in  its  frac 
tures. 

3.  Its  fpecific  gravity  to  water  is  as  8,500  to 

IOOO. 

4.  It  is  pretty  fixed  in  the  fire ;    but,  together 
with  the  fulphur  and  arfenic,  with  which  ies 
ore  abounds,  it  is  fo  far  volatile,  as  to  rife  in 
form  of  hairs  and  branches,  if  in  the  calcina 
tion  it  is  ^eft  without  being  ftirred. 

5.  It  calcines  .to  a  green  calx. 

6.  The  calx  is  not  very  fu'ible,  but,  however, 
tinges  glafs  of  a  tranfjparent  reddifli-brown  or 
jacinth  colour. 

Z  3  7-  It 


[    260    ] 

'  7.  It  diffulves  in  aqua-fortis,  aqua-regia,  and  the 
fpirit  of  fea-falt ;  but  more  difficultly  in  the  vi 
triolic  acid,  tinging  all  thefe  folutions  of  a  deep 
green  colour.  Its  vitriol  is  of  the  fame  co 
lour  ;  but  the  colcothar  of  this  vitriol,  as  well 
as  the  precipitates  from  the  folutions,  become 
by  calcination  of  a  light  green  colour. 

8.  Thefe  precipitates  are  diflblved  by  the  fpirit 
offal  ammoniac,  and  the  folution  has  a  blue 
colour ;  but  being  evaporated,  and  the  fediment 
reduced,  there  is  no  copper,  but  a  nickel  re- 
gulus  is  produced. 

9.  It  has  a  flrong  attraction  to  fulphur ;  fo  that 
when  its  calx  is  mixed  with  it,  and  put  on  a 
icorifying  teft  under  the  muffle,  it  forms  with 
the  fulphur  a  regule :   this  regule  refembles  the 
yellow  fteel-grained  copper-ores,  and  is  hard 
and  ihining  in  is  convex  furface. 

10.  It  unites  with  all  the  metals,  except  quick- 
filver  and  filver.     When  the  nickel  regulus  is 
melted  with  the  latter,  it  only  adheres  clofe  to 
it,  both  the  metals  lying  near  one  onother  on 
the  fame  plane;  but  they  are  eafily  feparated 
with  a  hammer.     Cobalt  has  the  ftrongeft  at 
traction  to  nickel,  after  that  of  iron,  and  then 
to  arfenic.     The  two  former  cannot  be  fepa 
rated  from  one  another  but  by  their  fcorifica- 
tion  ;  which  is  eafily  done,  fmce, 

11.  This  femnnetal  retains  its  phlogifton  a  long 
time  in  the  fire,  and  its  calx  is  reduced  by  the 
help  of  a  very  fmall  portion  of  inflammable 
matter:  it  requires,  how  ever,  a  red  heat  before 
it  can  be  brought  into  fufion,  and  melts  a  little 
fooner,  or  almoft  as  foon,  as  topper  or  gold, 
confequently  fooner  than  iron. 

Nickel  is  found. 
A  Native. 

This 


r    261    ] 

This  is  mentioned  by  Mr  Rinman  to  have 
been  lately  met  with  in  a  mine  of  cobalt  in  HefTe. 
It  is  very  heavy,  and  of  a  liver  colour,  that  is, 
dark  red.  When  pulverifed  and  roafted  under  a 
muffle,  it  forms  green  excrefcences,  and  fmokes  ; 
but  its  fraoke  has  no  particular  fmell  :  and  no 
fublimate,  whether  fulphureous  or  arfenic^l,  can 
be  caught.  It  is  foluble  in  acids,  and  the  folu- 
tion  is  green  ;  but  a  polifhed  iron  plate  difcovers 
no  copper. 

B.  In  form  of  a  calx.     Nickel  ochre,  aerated  nic- 
kel. 

i.  Mixed  with  the  calx  of  iron.  This  is  green, 
and  is  found  in  form  ©f  flowers  on  kupfer- 
nickel. 

C.  Mineral!  fed. 

1.  With  fulphurated  and  arfenicated  iron  and  co 
balt;  KupfirnickeL     This   is  of  a  reddiih  yel 
low  colour;  and  is  found, 

a.  Of  a  flaggy  texture. 

I.  Fine-grained  ;  and 

c.  Scaly.     Thefe  two  are  often  from  their  co 

lour    confounded   with    the    liver-coloured 

marcafite. 

2.  With  the  acid  of  vitriol.     This  is  of  a  beau 
tiful  green  colour,  and  may  be  extracted  out 
of  the  nickel  ochre,    or  efflorefcence    of   the 
Kupfernickel. 

For  a  fill;  account  of  this  femimetal,  fee  the  ar 
ticle.  NICKEL,  and 


VII.  Manganefe.     Mangane/ium. 

The  ores  of  this  kind  are  in  Swedifh  called 
Irunjlen  ;  in  Latin  fyderetf,  or  magmfia  nigr#,  in 
order  to  diftinguifh  them  from  the  magncfia  alba 
offictnalis  ;  and  in  French  manganefe,  &c. 
3.  Manganefe  confifts  of  afubftance  which  ofives 
a  colour  both  to  glaffes  and  to  the  folutiong 

of 


C    262    ] 

of  falls,   or,   which  is  the  fame  thing,   both 
to  dry  and  to  liquid  menft:  ua,  viz. 

a.  Borax,  which  has   diilolved  manganefe   in 
the  fire,  becomes  transparent,  of  a  reddifh 
brown  or  hyacinth  colour. 

b.  The  microcofmic  fait  becomes  tranfparent 
with  it,  of  a  crimfon  colour,  and  moulders  in 
the  air. 

e.  With  the  fixed  alkali,  in  compofitions  of 
glafc,  it  becomes  violet  ;  but  if  a  great 
quantity  of  manganefe  is  added,  the  glafs  is 
in  thick  lumps,  and  looks  black. 

d.  When  fcorified  with  lead,  the  glafs  obtains 
a  reddilh  brown  colour. 

c.  The  lixivium  of  deflagrated  manganefe  is  cf 
a  deep  red  colour. 

2.  It  deflagrates   with  nitre,  which  is  a  proof 
that  it  contains  fome  phlogiilon. 

3.  When    reckoned  to  be   light,   it    weighs  as 

much  as  an  iron  ore  of  the  fame  texture. 

4.  When  melted  together  with  vitreous  compo 

fitions,  it  ferments  during  the  folution  :  but  it 
ferments  in  a  ftill  greater  degree-when  it  is 
melted  with  the  microcofmic  fait. 

5.  It  does  not  excite  any  eiFervefcence  with  the 
nitrous    acid :    aqua-regia,    however,  extracts 
the  colour  out  of  the  black    manganefe,  and 
duTolves  likewife  a  great  portion  of  it,  which 
by  means  of  an  alkali  is  precipitated  to  a  white 
powder. 

6.  Such  colours  as  are  communicated  to  glafles 
by  manganefe,  are  eafUy  deftroyed  by  the  calx 
of  arfenic  or  tin  :  they  alfo  vaniih  of  themfelves 
in  the  fire. 

7>.  It  is  commonly  of  a  loofe  texture,  fo  as  to  co 
lour  the  fingers  like  foot,  though  it  is  of  a  me 
tallic  appearance  when  broken. 

Manganefe  is  found, 

[i.]  Nar 


[     263     3 

j~i.]  Native;  of  the  difcovery  and  qualities  of 
which,  an  account  is  given  under  the  article 
MANGANESE  in  its  alphabetical  order.  See  alfo 
CHEMIST  R  TL -Index. 

[2.]   Calciform. 

A.  Loofe  and  friable. 

a.  Black  ;  which  feems  to  be  weathered  or  de« 
cayed  particles  of  the  indurated  kind. 

B.  Indurated. 

i.)  Pure,  inform  of  balls,  whofe  texture  con- 
fids  of  concentric  fibres.     Pura  fpbarica  ra- 
dns  concentratis. 
a.  White  ;  very  fcarce. 
2.)   Mixed  with  a  fmall  quantity  of  iron. 
a.   Black  manganefe,  with  a  metallic  bright- 
nefs.     This  is  the  mod    common  kind, 
and  is  employed  at  the  glafs-houfes  and 
by  the  potters.     It  is  found, 

1.  Solid,  oi  a  flaggy  texture. 

2.  Steel-grained. 

3.  Radiated. 

4.  Cryftallifed,  in  form  of  coherent  hemi- 
fpheres. 

VIII.  Molybdena. 

A.  Lamellar  and  fliining,  its  colour  fimilar  to  that 
of  the  potter's  lead  ore. 

This  fubftance  refembles  plumbago  or  black- 
lead  ;  and  has  long  been  confounded  with  it, 
even  by  Cronftedt.  But  it  poffeiTes  very  different 
properties ;  in  particular, 

1.  Its  laminse  are  larger,  brighter:  and,  when 
thin,  flightly  flexible.     They  are  of  an  hexa 
gonal  figure. 

2.  It  is  of  a  lead  colour,  and  does  not  flrike  fire 
with  hard  fteel. 

3.  Its  fpeciftc  gravity  is  =  4,569,  according  to 
Kirwan  ;  and  457385,  according  to  Briflbn. 

12.  This 


£     264     ] 

4^  When  rubbed  on  white  paper,  it  leaves 
traces  of  a  dark  brown  or  bluiih  colour,  as 
the  plumbago  or  black  lead  does  ;  but  they 
are  rather  of  an  argentine  glofs  ;  by  which  cir« 
cumftance  tire  molybdena,  according  to  Dr 
d'Arcet,  may  be  eafily  diiVinguiihed  from 
black-lead,  as  the  traces  made  by  this  laft  are 
of  a  lefs  brilliant,  and  of  a  deeper  tinge. 

5.  In  an  open  fire,  it  is  almoft  entirely  volatile 
and    infufible.     Microcofmic    fait    or    borax 
fcarcely  affect  it ;  but  it  is  ailed  upon  with 
much  effervefcence  by  mineral  alkali,  and  forms 
with  it  a  reddiih  mafs,  tvhhh  fmells  of  fulphur. 

6.  It  confifts  of  an   acid  of  peculiar  nature  (fee 
CHEMISTRY-/^*.  )     united    to    fulphur.     A 
fmall  proportion  of  iron  is  commonly  found  in 
it,  but  this  feems  merely  fortuitous :   ico  parts 
of  molybdena  contain  about  45  of  this  acid 
and  55  of  fulphur. 

7.  It  is  decornpoied  either  by  detonation  with  ni 
tre,  or  by  folution  in  nitrous  acid. 

8.  This  acid  is  foluble  in  570  times  its  weight  of 
water    in    the  temperature    of  60;  the  folu 
tion  reddens  that  of  litmus,  precipitates  ful- 
phur  from  the  folution    of  liver  of  fulphur, 
&c.     The  fpecifk  gravity  of  the  dry  acid  is 
3,460. 

9.  This  acid  is  precipitable  from  its  folution  in 
water  by  the  Pruffian  alkali,  and  alfo  by  tinc 
ture  of  galls  :  the  precipitate  is  reddiih  brown. 

10.  If  this  acid  be  diftilled  with  three  times  its 
weight  of  fulphur,  it  reproduces  molybdena. 

1 1 .  The  folution  of  this  acid  in  water  unites  to 
fixed  alkalies,  and  forms  cryftallifable  falts  ;  as 
it  alfo  does^with  calcareous  earth,  magnefia, 
and  argil :  thefe  laft  combinations  are  difficult 
ly  foluble.     It  acts  alfo  on  the  bafc  metals,  and 
with  them  aiTumes  a  bluifh  colour. 


12.  This  folution  precipitates  filver,  mercury,  or 
lead,  from  the  nitrous  acid,  and  lead  from  the 
marine,  but  not  mercury. 

13.  It  alfo  precipitates  barytes  from  the  nitrous 
and  marine  acids,  but  no  other  earth.     Mo- 
lybdenous  barofelenite  is  foluble  in  cold  water. 

14.  This  acid  is  itfelf  foluble  in  the  vitriolic  acid 
by  theaffiilar.ee  cfheat;  and  the  folution  is 
blue  when  cold,  though  colourlefs  while  hot  ; 
it  is  alfo  foluble  in  the  marine  acid,  but  not  in 
the  nitrous. 

15.  Molybdena  tartar  and  ammoniac  precipitate 
all  metals  from  their  folutions  by  a  double  affi 
nity.     Gold,  fublimate    correfive,    zinc,    and 
manganefe,  are  precipitated  white  ;  iron  or  tin, 
from  the  marine  acid,  brown  ;    cobalt,  red  ; 
copper,  blue  ;  alum  and  calcareous  earth,  white. 

1  6.  This  acid  has  been  lately  reduced  by  Mr 
Hielm  ;  but  the  properties  of  the  regulus  thus 
obtained  are  not  yet  publifhed. 

17.  Mr  Pelletier  obtained    alfo  the    regulus  or 
molybdena,  by  mixing  its  powder  with  oil  into 
a  pafte,  and  expofing  it  with  powdered  char 
coal  in  a  crucible  to  a  very  violent  fire  for  two 
hours.  See  CHEMISTRY-/«^.V,  n°  14,  97, 

18.  This  femimetal  being  urged  by  a  ilrong  fire 
for  an  hour,  produces  a  kind  of  filvery  flowers, 
like  thofe  of  antimony. 

19.  Molybdena  is  faid  to  be  foluble  in  melted  ful* 
phur  ;  which  feems  highly  probable,    as  ful- 
phur  is  one  ot  its  component  parts. 

See    Farther  the  article  MOLYBDSNA,    and 

C  H  E  M  I  S  T  R  Y  - 


IX.  Wolfram.     IVolfranum,    Spuma  Lvpit  Lat.     See 
the  detached  article  WOLFRAM. 

This  mineral  has  the  appearance  of  manganefe, 
blended  with  a  fmall  quantity  of  iron  and  tin. 

i.  With 


[     266     ] 

I.  With  coarfe  fibres. 

a.  Of  an  iron-colour,  from  Altenberg  in  Sax 
ony.  This  gives  to  the  glafs  compofitions, 
and  alfo  to  borax  and  the  microcofmic  fait,  an 
opaque  whitifh  yellow  colour,  which  at  laft 
vanifhes. 

X.  Siderite.     1  See  thofe  words  in  the  order  of  the 

XI.  Saturnite.j      alphabet. 


APPENDIX. 

Of  Saxa  and  Petrifactions. 

THOUGH  the  Saxa,  and  foffils  commonly  called 
PetrifaBiom,  camu  t,  in  ftrictnefs,  be  ranked  in  a 
mineral  fyftem,  for  the  reafons  formerly  given  ;  yet 
as  thefe  bodies,  efpecially  the  latter,  occupy  fo  con- 
iiderable  a  place  in  mod  mineral  collections,  and  the 
former  muft  neceflarily  be  taken  notice  of  by  the  miners 
in  the  obfervations  they  make  in  fubterranean  geogra 
phy,  it  appeared  proper  to  fubjoin  them  in  fuch  an  or 
der  as  migfit  anfwer  the  purpofe  for  which  they  are  re 
garded  by  miners  and  mineralogifts. 

Order  I.     SAXA.     Petra. 

Thefe  maybe  divided  into  two  kinds, 

1.  Compound  faxa,  are  ftones  whofe  particles,  con- 
fitting  of  different  fubftances,  are  fo  exactly  fitted  and 
joined  together,  that  no  empty  fpace,  or  even  cement* 
can  be  perceived  between  them  ;  which  feems  to  indi 
cate,  that  fume,  if  not  all,  of  thefe  fubftances  have 
been  fo!  t  at  the  inftant  of  their  union. 

2,  Conglutinattd  ftones,  are  ftones  whofe  particles 
have    been    united  by  fome  cerwentitious   fubftance, 
which,  however,  is  feldom  perceivable,  and  which  of- 

been 


C    267    3 

been  hard,  \vorn  cfF,  and  in  loofe,  fmgle,  unfigured 
pieces,  before  they  were  united. 
I.  Compound  faxa. 

A.  Ophites.     Scaly    limeftone    with    kernels    or 
bits  of  ferpentine  ft  one  in  it. 

1.  Kolmord  marble.     It  is  white  and  green. 

2.  Serpentine  antico,  is  white,  with  round  pieces 
of  black  fteatites  in  it.     This  muft  not  be 
confounded  with  llizferpentino  verde.antico. 

3.  The  Haraldfio    marble.     White,   with  qua 
drangular  pieces  of  a  black  fteatites. 

4.  The    marmor>  pozzevem  di    Geno<va.     Dark 
green  marble,  with  white  veins.     This  kind"* 
receives  its  fine  polilh  and  appearance  from 
the  ferpentine  ftone, 

B.  Stellften  or  geJleljleiK.      Granitello. 

1.  Of  diftin<2:  particles.     In  fome  ofthefeths 
quartzofe  particlespredominate,  and  in  others 
the  micaceous :  in  the  laft  cafe  it  is  com 
monly  flaty,  and  eafy  to  fplit. 

2.  Of  particles  which  are  wrapt  up  in  one  ano 
ther. 

a.  Whitifh  grey. 

b.  Greeniih. 

c.  Reddiflh. 

C.  Norrka.     Murkjltn    of  the    Swedes.     Saxum 
cojnpojitiim  mica,  quarfzo,  et  gramto. 

1.  With  diftincl  garnets  or  fhirl. 

a.  Light  grey. 

b.  Dark  grey. 

c.  Dark  grey,  with  prifmatical,  radiated,  or 
fibrous  cockle  or  fhirl. 

2.  Wi^h  kernels  of  garnet-ftone. 
a.  Of  pale  red  garnet  ftone. 

The  firtl  of  this  kind,  whofe  flaty  ftrata  makes 
it  commonly  eafy  to  be  fplit,  is  employed 
for  mill-ftones,  which  may  without  difficul 
ty  be  accomplilhed,  if  land  is  firft  ground 
A  a  with 


[     268     ] 

with  them  ;  becaufe  the  fand  wearing  away 
the  micaceous  particles  on  the  furfaces,  and 
leaving  the  garnets    predominant,   renders 
the  ftone  fitter  for  grinding  the  corn. 
D.  The  whetftone,  Cos.     Saxum  compofitum   mca9 
quartxot  et  oran  argilla  martiali  in  nonnullis  fpe~ 
debus. 

1 .  Of  coarfe  particles. 
a.  White. 

t.  Light  grey. 

2.  Of  fine  particles. 

a.  Liver-brown  colour. 
l>.  Blackifh  grey. 
€.  Light  grey. 

</.  Black.     The  table-date,  or  that  kind  tifed 
for  large  tables  and  for  fchool  dates. 

3.  Of  very  minute  and  clofely  combined  par 
ticles.     The  Turkey-ftone.     This  is  of  an 
olive  colour,  and  feems  to  be  the  fined  mix 
ture  of  the  firft  fpecies  of  this  genus.     The 
beft  of  this  fort  come  from  the  Levant,  and 
are    pretty    dear.      The    whetftone    kinds, 
when  they  fplit  eafily  and  in    thin  plates, 
are  very  fit  to  cover  houfes  with,  though 
moft  of  them  are  without  thofe  properties. 

F.  Porphyry ;  Porphyntes.  Italorum  porfido. 
Saxum  compofitum  jafpide  etfe/t/pafo,  inter  dum  mica 
etbafahe  (D).  See  the  article  PORPHYRY. 


(D)  Great  part  of  the  hill  of  Bineves  in  Lochaber  is 
compofed  of  a  kind  of  porphyry.  It  is  remarkably 
fine,  beautiful,  and  of  an  elegant  reddifh  colour;  "in 
which  (fays  Mr  Williams)  the  pale  rofe,  the  blufh, 
and  the  yellowifli  white  colours,  are  finely  blended  and 
lhaded  through  the  body  of  the  ftone ;  which  is  of  a 
jelly  like  texture,  and  is  undoubtedly  one  of  the  fined 
and  moft  elegant  ftones  in  the  world.  On  this  hill  alfo 

k 


C    269    3 

a.  Its  colour  is  green,  with  light-green  feltfpat, 
Serpsntino  *oerde  ant'ico.  It  is  faid  to  have 
been  brought  from  Egypt  to  Rome,  from 
which  latter  place  the  fpecimens  of  it  now 
come. 

I,  Deep  red,  with  white  feltfpat. 

c.  Black,  \vithwhiteandredfeltfpat. 

d.  Reddiih  brown,  with  light  red  and  white 
feltfpat. 

r.  Dark  grey,    with  white  grains    of  ieltfpat 
alfo.     The    dark    red    porphyry  has  been 
moft  employed  for  ornaments  in  building  ; 
yet  it  is  not  the  only  one   known    by   the 
name  of  porfido,  th*o  Italians  applying  the 
fame  name  alfo  to  the  black  kind. 
G.  The  trapp  of  the  Swedes.     Saxum  compofitum 
jafplde  martiali  wo///,  feu  argilla  martialt  indurata. 
Seethe  article  TRAPP. 

This  kind  of  (lone  fometimes  conftitutes  or 
forms  whole  mountains  ;  as,  for  example,  the 
mountain  called  Hunneberg  in  the  province  of 
Weftergotland,  and  at  Drammen  in  Norway  ; 
but  it  is  oftener  found  in  form  of  veins  in  moun 
tains  of  another  kind,  running  commonly  in  a 
ferpentine  manner,  contrary  or  acrofs  to  the 
direction  of  the  rock  itfelf.  It  is  not  homoge 
neous,  as  may  be  plainly  feen  at  thofe  places 
where  it  is  not  preffed  clofe  together ;  but 
where  it  is  prerfed  clofe  it  feems  to  be  per 
fectly  free  from  heterogeneoits  fubftances.— 
When  this  kind  is  very  coarfe,  it  is  interfper- 


is  found  a  kind  of  porphyry  of  a  greenifli  colour,  with 
a  tinge  of  brownilh  red.  It  is  fmooth,  compact,  and 
heavy  ;  of  a  clofe  uniform  texture,  but  has  no  bright- 
nefs  when  broken.  It  has  angular  fpecks  ia  it  of  a 
white  quartzy  fubflance." 

A  a  2  fed 


[      270      ] 

fed  with  feltfpat ;  but  it  is  not  known  if  the 
finer  forts  likewife  contain  any  of  it.  Befides 
this,  there  are  alfo  fome  fibrous  particles  in  it, 
and  fomething  that  refembles  a  calcareous  (par ; 
this,  however,  does  not  ferment  with  acids, 
but  melts  as  eafy  as  the  ftone  itfelf,  which  be 
comes  a  black  folid  glafs  in  the  fire.  By  cal 
cination  it  becomes  red,  and  yields  in  aflays  1 2 
or  more  per  cent,  of  iron.  No  other  fart  of 
ore  is  to  be  found  in  it,  unlefs  now  and  then 
fomewhat  merely  fupeificial  lies  in  its  fiflures; 
for  this  (lone  is  commonly,  even  to  a  great 
depth  in  the  rock,  cracked  in  acute  angles,  or 
in  form  of  large  rhomboidal  dice.  It  is  em 
ployed  at  the  glafs  houfes,  and  added  to  the 
compofition  ot  which  bottles  are  made.  In 
the  air  it  decays  a  little,  leaving  a  powder  of  a 
brown  colour  ;  it  cracks  commonly  in  the  fire, 
and  becomes  reddiih  brown  if  made  red-hot.  It 
is  found, 

1.  Of  coarfe  chaffy  particles. 

a.  Dark  grey. 

b.  Black. 

2.  Coarfe -grained. 

a.  Dark  grey. 

b.  Reddiih. 

c.  Deep  brown. 

3.  Of  fine  imperceptible  particles. 

a.  Black.     The  touchftone  ;  Lapis  lytKus. 

b.  Bluifh. 

c.  Grey. 

d.  Reddifti. 

The  black  variety  (3.  a.)  is  fometimcs 
found  fo  compact  and  hard,  as  to  take  a 
polifti  like  the  black  agate  :  it  melts,  how- 
ever,  in  th'e  fire  to  a  black  glafs  ;  and  is, 
when  calcined,  attracted  by  the  load-Hone. 

If.   Am\-g« 


C    *7>    ] 

If.  Amygdalo'ides.  The  carpolithi  or  fruit-ftone 
rocks  of  the  Germans. 

It  is  a  martial  jafper,  in  which  elliptical  ker 
nels  of  calcareous  fpar  and  ferpentine  itone  are 
included. 

&.  Red,  with  kernels  of  white  limeftone,  and 
of  a  green  fteatites.  This  is  of  a  particular 
appearance,  and  when  calcined  is  attracted' 
by  the  loadftone  ;  it  decays  pretty  much  in 
the  air,  and  has  fome  affinity  with  the  trapp, 
and  alfo  with  the  porphyry.  There  are- 
fometimes  found  pieces  of  native  copper  in 
this  ftone. 
L  The  gronjlsn  of  the  Swedes. 

Its  bafis  is  horneblende,  interfperfed  with 
mica.  It  is  of  a  dark  green  colour,  and  in 
Smoland  is  employed  in  the  iron  furnaces  as  a 
flux  to  the  bog-ore. 

K.  The  granite.  Saxum  compofitum  fdtfpata^  mica 
et  qtiartzo,  qtibus  accidentalitcr  intcfdum  home- 
bknde  JlsatiteS)  granatus  et  Ixifalies  immixti  funt. 
Its  principal  conftituent  parts  are  felt  fpat,  or 
rhombic  quartz,  mica,  and  quartz.  See  the 
article  GRANITE. 

It  is  found, 

(  i.)  Loofe  or  friable.  This  is  ufed  at  the  Swed- 
ifh  brafs-works  to  caft  the  brafs  in,  and  comes 
from  France. 
(2.)  Hard  and  compact. 
a.  Red. 

i .  Fine-grained ; 
2    Coarfe-grained. 
I.  Grey,  with  many  and  various  colours  (E). 


(E)  Mr  Wiegleb  has  analyfed  a  fpecies  of  green  gra- 

r.ite  found  in  Saxony.  The  cryftals  aie  heaped  together, 

and  form  very  compact  layers;  the  colour  fometimes  an. 

A  a  3  olive 


C    27*    ] 

II.  Conglutinated  fa'xa. 

A*  Of  larger  or  broken  pieces  of  ftones  of  the  fame 
kinds  conglutinated  together.     Breccia. 


olive  green,  fbmetimes  refembling  a  pear,  and  fome- 
times  of  a  reddifh  brown :  fome  of  them  being  per 
fectly  tranfparent,  and  others  nearly  fo.  According 
to  Mr  Warren,  they  contain  25  per  cent,  of  iron ; 
whence  they  have  been  called  green  ore  of  iron.  An 
ounce  of  thefe  cryfbils  heated  red  hot  in  a  crucible  loft 
two  grains  in  weight,  and  became  of  the  colour  of 
honey.  The  remainder  was  put  into  a  retort,  and 
diftilled  with  marine  acid,  with  which  it  evidently  ef- 
fervefced.  The  refiduum  was  lixiviated  with  diftilled 
•water,  frefh  muriatic  acid  added,  and  the  diftillation 
and  lixiviation  repeated.  The  iron  precipitated  from 
this  lixivium,  and  reduced  partly  to  its  metallic  ftate, 
weighed  two  drachms.  M.  Wiegleb  concludes,  that 
the  fpecimen  contained  two  drams  26^-  grains  of  lime. 
From  further  experiments  he  concludes,  that  100 
parts  of  the  fubftance  contained  36.5  of  filiceous  earth  ; 
lime  30.8  ;  iron  28.7  ;  and  water  and  fixed  air  4.0. 

Scotland  is  remarkable  for  a  great  number  of  ex 
cellent  granites,  little  or  nothing  inferior  to  porphyry. 
Of  thefe  the  following  kinds  are  mentioned  by  Mr 
Williams. 

j.  The  grey  granite,  or  moor-Jlone  as  it  is  called  in 
Cornwall,  is  very  common  in  this  country.  In  fome 
places  it  (hows  no  marks  of  ftrata  ;  and  in  others  it  is 
difpofed  in  thick  unwieldly  irregular  beds,  which  are 
commonly  broken  tranfverfely  into  huge  mafTes  or 
blocks  of  various  fizes  and  ihapes.  There  is  a  great 
variety  in  this  kind  of  ftones  ;  fome  of  them  differing 
but  little  in  appearance  from  bafaltes  ;  others  are 
compofed  of  aim  oil  equal  parts  of  black  and  white 
grains,  about  the  fize  of  imall  peafe,  whence  it  is 
€ailed  feafy  whin  by  the  common  people.  In  Gal 
loway 


C    273    ] 

i.  Of  limeflone  cemented  by  lime. 

0.  Calcareous  breccia;  the  marmi  brecciati  of  the 
Italians. 


loway  and  other  places  it  frequently  has  a  longitudi 
nal  grain,  as  if  the  component  parts  had  been  all 
moved  one  way  by  a  gentle  flow  of  water.  When  this 
kind  of  granite  begins  to  undergo  a  fpontaneous  de- 
compofition  by  expoiure  to  the  atmoiphere,  we  ob- 
ferve  that  it  is  compofed  of  pretty  Urge  grains  of  the 
figures  of  cubes,  rhomboids,  &c.  fome  of  them  fo 
large  as  to  deferve  the  name  of  fragments;  and  the 
largeft  of  thefe  are  always  of  quartz  or  feldfpath,  and 
talc. 

2.  Reddifh    granite,  of  a    gellied  texture,  which, 
Mr  Williams  fays,  is  one  -of  the  fineft  and  rnoft  ele 
gant  ftones  in  the  world.     The  mountains  of  Bineves, 
he  fays,  are  principally  compofed  of  this  ftone;  and 
it  is  found  in  great  abundance  in  many  other  parts  "of 
Scotland,  but  he  never  faw  it  exhibit  any  marks  of 
{^ratification. 

3.  The  fine  reddifh  granites,  in  which  feveral  fine 
fhades  of  colours  are  blended  together,  not  fpread  out 
in  tints  as  in  the  former.     Neither  this  nor  the  former 
are  ftratified  :  "  On  the  contrary  (fays  our  author), 
both  exhibit  fuch  a  degree  of  uniform  regularity,  that 
in  fome  places  there  is  no  difference  between  a  ftone 
and    a  mountain,  excepting  only   in   magnitude;  as 
many  mountains  of  granite  are  nothing  more  than  one 
regularly  uniform  mafs  throughout,  in  which  not  the 
Jeaft  mark  of  a  bed  is, to  be  fjeen,  nor  hardly  a  crack 
or  fifTure,  unlefs  it  be  at  the  edge  of  fome  precipice  or 
declivity.      Thefe  two  varieties  of  elegant  red  granite 
are  met  with  in  the  Highlands  and  Lowlands  of  Scot 
land,  in  Galloway,  and  many  other  places.     We  of 
ten  find  malTes  of  talc  fo  large  in  this  fecond  variety, 
that  fome  of  them  may  be  called  fragments,  not  dif- 

pofed 


C    274    1 

When  thefe  kinds  have  fine  colours,  they 
are  polifhed  and  employed  for  ornaments  in 
architecture  and  other  ceconomical  ufes. 


pofed  in  any  order,  but  higgledy-piggledy  through 
the  body  of  the  flone. 

4.  Stratified  reddiih  granite,  refembling  the  third  in 
colour  and  quality,  but  not  always  quite  fo  pure  or 
free  from  admixture  of  other  ftony  matter  of  a  dif 
ferent  quality.     This  variety  frequently  contains  lar 
ger  and  fmaller  fragments  of  fine  laminated  talc.     Mr 
Williams,  however,  has  feen  this  kind  of  granite  dif- 
pofed  in  pretty  regular  ftrata  in  the  (hires  of  Moray 
and  Nairn,  and  other  parts  of  Scotland. 

5.  Granite  of  a  white  and  whitifh  colour,  generally 
of  a  granulated  texture,  containing  a  great  quantity 
of  mica,  or  fmall-leaved  talc,  and  the  grains  of  quartz 
Ibmetimes  large  and  angular.     This  variety  is  fubjecl 
to  fpontaneous  decompofition ;    part   frequently  dif- 
folves  and  falls  into  lakes,  in  fuch  an  exceedingly  fine 
and  attenuated  date,  that  it  does  not  fink  in  the  water. 
"  I  have  found  (fays  Mr  Williams)  this  fubftance  in 
many  places  where  water  had  been  accidentally  drain 
ed  off,  refembling  fine  (hell  marie,  only  much  lighter. 
When  thoroughly  dry,  it  is  the  lighted  foflile  fubrtance 
I  ever  handled  j  and,  when  blanched  with  rain,  it  is  as 
\vhite  as  mow.     This  variety  of  granite  is  either  not 
flratified,    or  exhibits  thick  irregular  beds.     It  fre 
quently  contains  a  considerable  quantity  of  talc,  in 
rnafTes  and  fcales  too  large  to  be  called  mica." 

Our  author  is  of  opinion,  that  this  fine  white  fub 
ftance  produced  from  the  decompofition  of  the  gra 
nite,  is  the  true  kaolin  of  the  Chinefe,  one  of  the  com 
ponent  parts  of  porcelain  ware.  "  The  authors  of 
the  Hiftory  of  China  (fays  he)  informs  us,  that  the 
fine  porcelain  ware  is  compofed  of  two  different  foffile 
fiabftances,  called  by  them  pstuntfs  and  kaolin.  We  are 

iurther 


C    *75    ] 

b.  The  lumachdla  of  the  Italians,  or  fhell  mar 
bles.  Thefe  are  a  compound  of  fhells  and 
corals,  which  are  petrifisd  or  changed  into 


further  told,  that  the  petuatfe  is  a  fine  white  vitref- 
clble  ftone,  compact  and  ponderous,  and  of  confider 
able  brightnefs  in  the  infide  when  broken,  which  they 
grind  to  a  fine  powder;  and  that  the  kaolin  is  not  a 
{tone,  but  a  fine  white  earthy  fubftance,  not  verifiable, 
at  lead  not  in  the  heat  of  a  common  potter's  fimiace  ; 
that  they  mix  the  kaolin  and  the  flour  of  the  petuntfe 
together,  and  form  a  pafte  of  this  mixture,  which  they 
mould  into  all  forts  of  porcelain  ve/Tels.  Now,  frora 
the  beft  accouats  of  this  matter  which  I  have  been 
able  to  obtain,  after  a  good  deal  of  fearc'h  and  inqui 
ry,  it  appears  to  me,  that  the  fediment  which  I  have 
mentioned  above  is  the  true  kaolin;  and  that  as  the 
fine  white  glafly  quartz,  which  is  found  in  irregular 
mafTes,  and  in  irregular  difcontinuous  veins  or  ribs, 
in  fome  of  the  rocks  of  fchidus,  is  the  true  petuntfe; 
£nd  if  this  obfervation  is  really  true,  it  deferves  to  be 
remarked,  that  Scotland  is  as  well  furmihed  with  the 
beft  materials  for  making  fine  porcelain  as  moil  coun 
tries  in  the  world.  The  ipecies  of  quartz  which  I  fup- 
pofe  to  be  petuntfe  is  of  a  pure  fine  unih.i  m  glafly  tex 
ture,  femitranfparent,  and  of  a  pure  fnowy  whitenefs. 
A  broken  piece  of  this  (tone,  and  a  newly  broken 
piece  of  fine  porcelain,  are  very  like  one  another. 
There  is  a  great  quantity  of  petuntfe,  or  pure  white 
quartz,  in  many  places  of  Scotland,  particularly  in 
the  north  and  Highlands.  There  is  a  confiderable 
quantity  of  it  upon  th?  fhore  and  wa'fhed  by  the  tide 
between  Banff  and  Cullen,  generally  in  pretty  large 
maffes  in  rocks  of  bluifh  fchidus;  and  to  the  befl  of 
my  memory  it  is  very  fine  of  the  kind.  There  is  alfo 
a  confiderable  quantity  of  it  in  difcontinous  ribs  ;md 
LiafTes,  in  rocks  of  blue  fchift,  about  three  or  four 

miles 


C    276   ] 

lime,  and  conglutinated  with  a  calcareous 
Jubilance     When  they  have  many  colours, 


miles  north  of  Callendar  in  Monteith,  upon  the  fide  of 
the  high  road  which  runs  parallel  to  Lochleodunich, 
which  I  think  alfo  very  fine.  In  fome  places  this  fort 
of  quartz  is  tinged  with  a  rfefh  colour  from  the  neigh 
bourhood  of  iron,  which  renders  it  unfit  for  porcelain  ; 
but  there  is  plenty  to  be  found  of  a  pure  white  in  al- 
moft  all  parts  of  Scotland,  without  any  mineral  tinge 
whatever.  The  kaolin  is  perhaps  as  plentiful  in  Scot 
land  as  the  petuntfe,  there  being  many  extenfive  lakes 
eafily  drained,  which  contain  a  confiderable  depth  of 
it ;  and  moreover,  it  is  to  be  found  in  many  places 
that  have  been  lakes,  which  are  now  laid  dry  by  ac 
cident.  There  is  a  quantity  of  kaolin  about  ico  yards 
below  the  high  road  upon  the  fouth  fide  of  a  bridge, 
about  a  mile  and  a  half  or  two  miles  fouth  of  the  inn 
of  Aviemore  in  the  Highlands.  It  lies  beneath  a  ftra- 
tum  of  peat  bog,  in  a  place  which  has  been  a  lake, 
but  is  now  drained  by  the  river  Spey  cutting  through 
one  fide  of  the  mound  which  formed  the  lake. — There 
is  more  than  one  (Iratum  of  the  kaolin  in  this  place, 
and  fome  of  it  is  exceedingly  white,  especially  when 
blanched  by  the  rain  ;  and  there  is  a  white  granite  rock 
up  the  rivulet,  at  fome  diftance  above  the  bridge,  the 
decomposition  and  dilfolution  of  which  is  fuppofed  to 
produce  this  fine  and  curious  fediment.  Several  lakes 
in  the  Highlands  of  Scotland  are  nearly  full  of  kaolin. 
One  of  them  is  fituated  in  the  country  of  Stratherig  in 
Invernefs-fhire,  lefs  than  a  mile  north  of  the  public 
road,  and  upon  the  weft  fide  of  the  farm  of  Drimin. 
It  is  a  pretty  long  lake,  and  there  is  a  confiderable 
depth  of  kaolin  in  it,  which  may  be  drained  at  a  mo 
derate  expence  ;  and,  if  I  remember  well,  the  granite 
rocks  which  furround  it  are  pretty  white  and  fine.  If 
the  kaolin  originates  from  coloured  granite,  it  is  good 

for 


C    277    ] 

they  are  called  marbles,  and  employed  for  the 
fame  purpofes  as  the  preceding  *  (F). 


for  nothing,  efpecially  if  it  contains  the  lead  tinge  of 
iron,  becaufe  this  will  difcolour  and  fpoil  the  beauty 
of  the  porcelain  ;  but  wherever  white  granite  is  found 
compofed  of  quartz,  feldfpath,  and  mica,  without  any 
admixture  of  ihirl,  and  efpecially  iron,  the  kaolin 
fhould  be  diligently  fought  after  in  that  neighbour 
hood.  Lochdoon,  in  Galloway,  is  faid  to  contain  a 
great  quantity  of  kaolin.  It  was  drained  fome  years 
ago  on  the  fuppofition  of  its  containing  (hell  marie  ; 
but  on  trying  the  fubftance  contained  in  it,  it  was  found 
not  to  be  marie  but  kaolin.  Thefe  fubftances  may 
eafily  be  miftaken  for  one  another  at  firft  ;  but  they  are 
cafily  diftinguiihed  by  trying  them  with  acids, the  marie 
readily  effervefcing  with  the  weakeft,  and  the  kaolia 
not  at  all  with  the  ftronge-H:  acid  liquors." 

6.  Grey  compofite  granite  is  a  very  beautiful  (lone, 
and  when  broken  looks  as  if  compofed  of  fmall  frag 
ments  of  various  fizes  and  fhapes,  not  unlike  calve' s- 
head  jelly.  When  polifhed,  the  fragments  appear  as 
if  fet  or  inlaid  in  a  fine  pellucid  or  water  coloured  mat 
ter.  There  is  a  (ingle  (Iratum  of  very  curious  com 
pofite  granite,  a  little  to  the  weft  of  Loffiemouth,  in 
the  county  of  Moray,  in  Scotland,  of  about  fix  or 
eight  feet  thick.  It  is  compofed  chiefly  of  grains  and 
fragments  of  various  bright  and  elegant  colours,  moft 
of  which  are  as  large  as  peafe  and  beans,  all  fine,  hard, 
andfemipellucid ;  there  is  about  an  eighth  part  of  good 
lead  ore  in  the  compofition  of  this  ftone,  of  the  kind 
commonly  called  potter's  ore  ;  and  it  is  likewife  re 
markable,  that  there  is  no  other  granite  in  that  neigh 
bourhood  but  this  fmgle  ftratum,  all  the  ftrata  above 
and  below  it  being  moftly  a  coarfe,  imperfect,  grey 
fund-done. 

7.  Gra- 
*  ?ee  note  (r)  In  page  279, 


2.  Of  kernels  of  jafper  cemented  by  a  jafpery  fub- 
ftance.  Breccia  jafpidea.  Dlojpro  Irecciato  of 
the  Italians. 


7.  Granite  of  a  loofe  friable  texture,  fubjecl:  to  fpon- 
taneous  decompofition,  and  redu&ion  to  granite  gra 
vel.     There  is  a  remarkable  rock  of  this  kind  near  the 
Queen's -ferry  in  Scotland,  on  the  road  to  Edinburgh, 
which    appears  in  prodigious  thick  irregular   ftrata. 
This  rock  feems  to  be  compofed  chiefly  of  quart/, 
fhirl,  and  force  iron ;  and  produces  excellent  mate 
rials  for  the  high  roads. 

8.  In  many  parts  of  the  north  of  Scotland,  in  the 
Highlands,  and  in  Galloway,  there  is  found  an  ex 
cellent  fpecies  of  grey  granite,  compofed  chiefly  of  red 
and  black  coloured  grains.     This  is  a  fine  and  very 
durable  ftone,  v^ry  fit  for  all  kinds  of  architecture. 

In  fpeakmg  of  thefe  ftones,  Mr  Williams  obferves, 
that  the  finer  and  moft  elegant  red  granites,  and  the 
fineft  granite-like  porphyries,  fo  much  refemble  one 
another,  that  he  does  not  attempt  to  diftinguifh  them  ; 
and  Scotland  is  remarkable  for  a  great  number  and  va 
riety  of  them,  "  The  elegant  reddiih  granite  of  Bi- 
neves,  near  Fort  William  (fays  he),  is  perhaps  the  bed 
and  moft  beautiful  in  the  world  ;  and  there  is  enough 
of  it  to  ferve  all  the  kingdoms  on  earth,  though  they 
were  all  as  fond  of  granite  as  ancient  Egypt.  There 
are  extenfive  rocks  of  red  granite  upon  the  fea-fhore 
to  the  weft  of  the  ferry  of  Ballachylifh  in  Appin,  and 
likewife  at  -Strontian,  as  well  as  many  other  parts  of 
Argylefhire.  I  have  feen  beautiful  red  granite  by  the 
road  fide,  near  Dingwall,  and  in  feveral  other  parts 
of  the  north  of  Scotland,  which  had  been  blown  to 
pieces  with  gun-powder,  and  turned  off  the  fields. 
There  are  extenfive  rocks  of  reddifti  granite  about 
Peterhead  and  Slains,  and  both  of  red  and  grey  gra 
nite  in  the  neighbourhood  of  Aberdeen.  The  hill  of 
3  Cruffel 


[     299     ] 

Of  this  kind  fpecimens  from  Italy  are  fccn 
in  collections.  A  coarfe  jafper  breccia  is  faid 
to  be  found  not  far  from  Frejus  in  Provence  in 
France. 


Cruffel  in  Galloway,  and  feveral  lower  hills  and  ex- 
tenfive  rocks  in  that  neighbourhood,  are  of  red  and 
grey  granite,  where  there  are  great  varieties  of  that 
Hone,  and  many  of  them  excellent.  Upon  the  fea  ihore 
near  Kinnedore,  weft  of  Loffiemouth,  in  Moray,  there 
is  a  bed  of  ftone  about  eight  feet  thick,  which  I  think 
ihonld  be  called  a  compofite  granite.  It  is  compofed 
of  large  grains,  or  rather  fmall  pieces  of  bright  and 
beautiful  ftnnes  of  many  different  colours ;  and  all  the 
ilony  parts  are  exceedingly  hard,  and  fit  to  receive 
the  higheft  polifh.  About  a  fiith  or  eighth  part  of  it 
nlfo  confifts  of  lead  ore,  of  that  fpecies  called  potter's 
ore.  The  feparate  ftony  parts  compofmg  this  ftratum 
are  all  hard,  fine,  folid,  and  capable  of  the  moft  bril 
liant  polifh  ;  and  if  iolid  blocks  can  be  raifed  free  from 
all  cracks  and  blemiuhes,  I  imagine,  from  the  beauty 
and  variety  of  colours  of  the  ftony  part,  and  the  quan 
tity  of  bright  lead  ore  which  is  blended  through  tha 
compofition  and  body  of  the  (lone,  that  this  would  be 
u  very  curious  and  beautiful  ftone  when  polifhed.'' 

(F)  The  ftones  called  Lur/i  Belmontii  or  Paracelji, 
have  fome  fimilarity  in  their  form  to  the  breccia,  a.  b.  : 
for  they  are  compofed  of  various  lumps  of  a  maily 
whitifti-brown  matter,  feparatcd  into  a  great  number 
of  polygonous  compartment?,  of  various  fixes,  formed 
of  a  whitifh -yellow  cruft  of  a  red  calcareous  fpar, 
fnmetimes  pyritous,  which  often  rife  a  little  above  the 
external  furface,  and  inclofe  each  of  them  on  the  in- 
fide.  According  to  Bomare,  the  ludvt Jtel/atui  Lclmon- 
tii,  found  in  the  county  of  Kent,  is  covered  with  a 
kind  of  ftriated  felenite  refembling  the  zeolite.  They 
are  for  the  moft  part  of  a  globcfe  figure,  feldom  fl.it, 
B  b  but 


3-  Of  filiceous  pebbles,  cemented  by  a  jafpery 
fubftance,  or  ibmething  like  it.  The  plum- 
pudding  ftone  of  the  Englifh  ;  Breccia  Jilicea. 
Its  bafis,  which  at  the  fame  time  is  the  ce 
ment,  is  yellow;  wherein  are  contained  fmgle 
flinty  cr  ag*ty  pebbles,  cf  a  grey  colour  or 
variegated.  This  is  of  a  very  elegant  appear 
ance  when  cut  and  polifhed :  it  is  found  in 
England  and  Scotland  (G). 


but  often  convex  on  the  outfide;  and  fornetimes  with 
a  concave  furface. 

According  to  Wallerius,  the  Indus  helmontii  lofes  by 
calcination  about  half  of  its  weight ;  and,  on  being 
urged  by  fire,  is  melted  into  a  black  glaffy  flag.  It 
effervefces  (Irongly  with  aqua-fortis,  and  this  folution 
is  of  a  yellow  colour.  But  what  feems  very  extra 
ordinary,  by  adding  to  it  fome  oil  of  tartar  per  ddi- 
quium,  bubbles  are  produced,  from  which  a  great  num 
ber  of  flender  black  threads  or  filaments  are  produced, 
flicking  like  a  cobweb  to  the  fides  and  bottom  of  the 
veffel. 

Thefe  (tones  are  found  quite  feparate  by  themfelves, 
as  well  as  various  ft.ilagmites  and  cruftaceous  bodies, 
on  the  ftrata  of  argillaceous  earth,  in  various  parts 
of  Europe,  chiefly  in  Lorrain,  Italy,  England  (in  the 
counties  of  Middlefex  and  Kent),  and  elfewhere. 

Wallerius  ranges  the  Indus  helmontn  among  the  tophi, 
in  the  Spec.  425.  of  his  fy  ft  em  of  Mineralogy.  Para- 
celfus  had  attributed  to  thefe  ftones  a  lithontriptic 
power, tind  Dr  Grew  fays  that  tkey  are  diuretic;  but 
there  is  not  the  leail  proof  of  their  ^really  poficffing 
fuch  qualities. 

(G)  The  breccia  ftratum,  or  plumbpudding-rock, 
exhibits  a  (ingular  appearance  as  it  lies  in  the  ground  ; 
being  compoied  of  water-rounded  ftones  of  nil  quali 
ties  and  of  all  fizes,  from  fmall  gravel  up  to  large 

rouudsd 


4.  Of  quartzofe  kernels  combined  with  an  un 
known  cement.     Breccia  quartzvfi. 

5.  Of  kernels  of  feveral  different  kinds  of  flones. 
Breccia  faxofa . 


rounded  (tones  of  feveral  hundreds  weight  each ;  the 
interfaces  being  filled  up  with  lime  and  fund.  It  fre 
quently  alib  contains  lime  and  iron.  Sometimes  it  ex 
hibits  a  grotefque  and  formidable  appearance ;  con 
taining  many  large  bullets  of  various  fizes  and  fhape<, 
without  any  marks  of  regular  {^ratification,  but  look. 
ing  like  one  vaft  mafs  of  bullets  of  unequal  thicknefs ; 
and  in  this  manner  frequently  fwelled  to  the  fize  of  a 
confiderable  mountain.  It  is  frequently  cemented 
very  ftrongly  together  ;  fo  that  parts  of  the  hills  com- 
pofed  of  it  will  frequently  overhang  in  dreadful  pre 
cipices,  lefs  apt  to  break  off  than  other  rocks  in  the 
fame  (ituation ;  one  reafon,  for  which,  befides  the 
ftrength  of  the  cement,  is,  that  the  breccia,  when 
compofed  of  bullsts,  is  lefs  fubjecl  to  fiflures  and  cut 
ters  than  other  rocks;  being  frequently  found  in  one 
folid  mafs  of  great  extent  and  thicknefs.  Some  of 
the  plumpudding-rocks  are  made  up  of  fmallsr  parts, 
coming  near  to  the  fize  of  coarfe  gravel.  It  is  evident 
however,  that  all  the  parts  of  the  breccia,  whether 
coarfe  or  fine,  have  been  rounded  by  agitation  in  wa 
ter,  as  the  rocks  differ  nothing  in  appearance  from  the 
coarfer  and  finer  gravel  found  upon  the  beach  of  the 
fea,  excepting  only  that  the  parts  are  ftrongly  cement 
ed  together  in  the  rocks,  and  are  loofe  upon  the 
fhores  of  the  ocean. 

Some  of  the  breccia  is  compofed  of  finely  rounded 
(tones  of  various  and  beautiful  colours,  about  the  fr/.e 
of  plums  or  nuts,  all  very  hard  and  fine.  Were  this 
fpecies  fawed  and  poliflied,  it  would  appear  as  beauti 
ful  and  elegant  as  any  ftone  in  Europe ;  much  refem- 
bling  mofaic  work  in  fmall  patterns. 

B  b  2.  la 


C    302    ] 

Of  kernels  of  porphyry,  cemented  by  a  por 
phyry  or  coarie  jafpery  fubftance;  Bteccia 
porphyrea. 


In  general,  the  breccia  is  regularly  ftratified  or  not 
according  to  the  fize  of  the  component  parts  of  the 
itone.  Such  rocks  as  are  compofed  of  round  gravel 
and  fmall  bullets  are  generally  very  regular  in  their 
iUtificatien,  while  thofe  which  contain  bullets  fome- 
what  larger  in  fize  are  commonly  difpofed  in  thick 
and  coarie  beds,  and  fuch  rocks  as  are  made  up  of 
the  largeft  kind  of  bullets  feldom  (how  any  marks  of 
jft ratification  at  all. 

Among  many  other  places  in  Scotland,  where  brec 
cia  or  pudding-ftone  abounds,  there  are  extenfive  rocks 
and  high  cliffs  cf  it  upon  the  fouth  (hore  at  the  weft 
end  of  the'Pentland  Frith,  to  the  weft  ward  of  Thurib 
in  Caithnefs,  which  ftretch  quite  acrofs  the  county  of 
Caithness  into  Sutherland ;  and  in  Sutherland  as  well 
as  Caithnefs,  this  reck  is  of  a  rough  contexture,  and 
appears  in  pretty  high  hills,  deep  glens,  overhanging 
rocks,  and  frightful  precipices,  to  the  weft  of  Brcra, 
Dunrcbin,  and  Dornoch,  which  gives  it  a  grotefque 
and  formidable  appearance  in  that  country.  This 
range  of  breccia  ftretches  alfo  quite  through  Suther 
land,  and  likewife  through  Rofsfhire,  the  weft  fide  cf 
Ferndonald,  and  Ding  wall,  where  it  exhibits  the  very 
iame  phenomena  as  in  Sutherland  and  in  Caithnefs. 
It  continues  the  fame  longitudinal  line  of  bearing, 
which  is  nearly  from  north-eaft  to  fcuth-weft,  quite 
through  the  highland  countries  of  Invernefs  and  Perth- 
ihire;  and  it  forms  confiderable  hills,  and  very  high 
and  rugged  rocks,  upon  both  fides  of  that  beautiful 
piece  of  frefh  water  Lochnefs.  Much  of  the  ftone  here 
as  well  as  in  other  places  in  this  range,  is  compofed  of 
large  bullets ;  the  rock  is,  very  hard  and  ftrong,  and 
\t  hangs  in  frighthful  precipices  upon  both  fides  of  the 

lake 


b.  Of    kernels   of   feveral  faxa;    Breccia    indeter 
minate. 

c.  Of  conglutinated  kernels  of  fandftone ;  Brec 
cia  arenacea.     This  kind  confiits  of  fandltone 
kernels,  which  have  been  combined  a  fecorid 
time  together. 

The  abovementioned  breccue  of  themfelves  mud 
demand  the  diilinctions  here  made  between, 
but  which  perhaps  may  fcem  to  be  carried  too 
far,  fmce  their  particles  are  fo  big  and  plain 
as  to  be  eafily  known  from  one  another.  Thefe 
Hones  are  a  proof  both  of  die  fubverfions 
which  the  mountains  in  many  centuries  have 
undergone,  and  of  fome  hidden  means  which 
nature  makes  ufe  of  in  thus  cementing  diffe 
rent  kinds  of  ftones  together.  Any  certain 
bignefs  for  the  kernels  or  lumps  in  fuch  com 
pounds,  before  they  deferve  the  name  of  breccia? 
cannot  be  determined,  becaufe  that  depends 
on  a  comparifon  which  every  one  is  at  liberty 
to  imagine.  In  fome  places,  the  kernels  of 
porphyry  have  a  diameter,  of  fix  feet,  while  in 


lake,  through  which  rock  General  Wade  cut  a  fine  mi 
litary  road  upon  the  fouth  fide  of  the  lake,  at  a  great 
expence  of  time,  labour,  and  gun-powder.  Thefe  rocks 
are  leen  ftretching  through  the  mountains  of  Stratherig 
into  Badenoch,  where  it  forms  a  remarkable  rock  and 
precipice  called  Craigdow  or  the  Black  Rock.  The 
lame  range  is  again  feen  farther  towards  the  fouth- 
weft,  in  feveral  places  to  the  fouth  of  the  Black  Mount, 
and  in  the  country  of  Gienoichy  in  Argyleihire  :  and 
Mr  Williams  fuppofes,  that  the  longitudinal  line  of 
this  rock,  fp  far  as  it  has  been  juft  pointed  out,  is 
little  lefs  than  200  miles,  and  in  fome  places  it  fpreads 
eight  or  ten  miles  in  what  may  be.  called  the  latitudinal 
line  acrofs  the  bearing  of  the  rocks. 
B  b  3 


C    304    ] 

citicrs  they  are  no  bigger  than  walnuts.  Some 
times  they  have  a  .  prp.greffive  fiz6   down   to 
that  of  a  find  frrdfcone.     Mult  of  this  kind  of 
ftcne  is  fit  for  ornaments,  though  the  work- 
manihip  is  very  difficult  ar.d  coftly. 
JS.  Conglutinated  ftones  of  granules  or  fands  of  dif 
ferent  kinds.      Sandftone;  Lapis  arenaceus. 

In  this  divifion  are  reckoned  thofe  which  confift 
of  fuch  minute  particles,  that  all  of  them  cannot 
eafily  be  difcovered  by  the  naked  eye.  The  great- 
eft  part,  however,  confift  of  quartz  and  mica; 
which  fubftances  are  the  moft  fit  to  be  granulated, 
withput  being  brought  to  a  powder. 

1.  Cemented  by  clay. 

a.  With  an  apyrous  or  refractory  clay.     This 
is  of  a  loofe  texture;  but  hardens,  and  is  very 
refractory  in  the  fire. 

b.  With  common  clay. 

2.  With  lime ;  refembles  mortar  made  with  coarfe. 
fand. 

a.  Confiding  of  tranfparent  and  greenifli  grains 

of  quart'/  and  white  limeftone. 
#•  Of  no  vifible  particles.     This  is  of  a  leofe 

texture,  and  hardens  in  the  air. 

3.  With  an  unknown  cement. 
a.  Loofe. 

I'..  Harder. 

c.  Compact. 

d.  Very  hard. 

4.  Cemented  by  the  ruft  or  ochre  of  iron,     is 
found  in  form  of  loofe  ftones  at  feveral  places, 
and  ought  perhaps  to  be  reckoned  among  the 
miner  a  arenacea  or  fand  ores;  at  leaft  when  the 
martial  ochre  makes  any  confiderable  portion 
of  the  whole. 

5-,  Giit-ftone.  This  is  of  greater  orlefs  hardnefs, 
moftly  of  a  grey,  and  fometimesof  a  yellowifli 
colour;  contpofed  of  a  filiceous  and  micaceous 

fand 


[     3°5-   3 

fand,  and  rarely  of  a  fparry  Knd,  with  greater 
or  lefler  particles  clofely  compacted  arid  united 
by  an  argillaceous  cement.  I1"  .*;  -.  ibme 
fparks  with  flee),  is  mdilToiuble  i\  r  •,': . .  ruoft 
part  in  acids,  and  vitrifiab?.:  in  a  ilrong  fire. 
It  is  uicd  for  iT.iililones  and  whetftcnes,  fome- 
times  for  filtering  ftones  and  for  building.  Fa- 
Irom. 

N.  B.  The  argillaceous  girt  has  been  before 
defcribed,  p.  89.  col.  i. 

6.  Elatlic.  A  fmgular  fpecies  of  fandftone,  of 
which  a  fpecimen  was  iliown  fome  years  ago  to 
the  Royal  Academy  of  Sciences  at  Paris  by  the 
Baron  de  Dietrich.  It  is  flexible  and  elaftic; 
and  confifts  of  fmall  grains  of  hard  quartz,  that 
ftrike  fire  with  tempered  fteel,  together  with 
fome  micaceous  mixture.  The  elafticity  feems 
to  depend  on  the  micaceous  part,  and  foftnefs 
of  the  natural  gluten  between  both.  It  is  faid, 
that  this  elaftic  ftoae  was  found  in  Brazil,  and 
brought  to  Germany  by  his  excellency  the 
Marquis  de  Lavradio. 

There  are  alfo  two  tables  of  white  marble, 
kept  in  the  palace  Borghefe  at  Rome,  which 
have  the  fame  property,  But  the  fparry  par 
ticles  of  their  fubitance,  though  tranfpa:rent, 
are  rather  foft;  may  be  eafily  feparated  with 
the  nail,  and  effervefce  with  aqua-fortis;  and 
there  is  alfo  in  it  a  little  mixture  of  fmall  par 
ticles  of  talc  or  mica.  Se  Journ.  de  Phyf. 
for  Ocl»  1784,  p.  275.  See  alfo  the  article 
MARBLE  (Elaftic.) 

C.  Stones  and  ores  cemented  together;  Mine ra  are- 
nacex. 
I.  Of  larger  fragments. 

a.  Mountain  green,  or  utricle  montanum  cuprir 
and  pebbles  cemented  together,  from  Sibe 
ria^ 

b.  Potter* 


C 

1.  Potters  lead-ore,  with  limeftone,   Hate-ker 

nels,  and  (hells. 
c.  Yellow  or  marcafitical  copper  ore,  with  fmali 

pebbles. 
2.  Of  fmaller  pieces. 

a.  Potter's  lead-ore  with  a  qua*  tzofe  fand. 

b.  Mountain  green  with  fand  from  Siberia, 

c.  Cobalt  ore  with  fand. 

d.  Martial  ochre  with  fand. 

Order  II.  MINERAL  CHANGES,  or  PETRIFACTIONS. 

THESE  are  mineral  bodies  in  the  form  of  animals  or 
Vegetables,  and  for  this  reafon  no  others  belong  to 
this  order  than  fuch  as  have  been  really  changed  from 
the  fubjefts  of  the  other  two  kingdoms  of  nature. 
I.    Earthy  changes;   "Terra  tarvattz- 

A.  Extraneous  bodies  changed  into  a  lime  fubftance, 
or  calcareous  changes;  Larv<£  ca'carca. 
(i.)  Loofe  or  friable.     Chalky  changes;  Crete 


a.  In  form  of  vegetables. 

b.  In.  form  of  animals. 

i.  Calcined  or  mouldered  fliells  ;  Humus  con- 

cbaceus. 
(2.)  Indurated  ;  Petrifafta  cakarea. 

a.  Changed  and  rilled  with  folid  limeftome. 

1.  In  form  of  animals. 

2.  In  form  of  vegetables. 

1.  Changed  into  a  calcareous  fpar;  PetrifaSa 

calcarea  fpatofa. 
,:.        i  .  In  form  of  animals. 

2.  In  form  of  vegetables. 

.  Extraneous  bodies  changed  into  a  flinty  fubftance. 
Siliceous    changes;    Larvae  Jillcca.      Thefe    are, 
like  the  flint, 
(i)  Indurated. 

a-  Changed  into  flints. 

r.  Car- 


C    S°7'-    1 

1 ,  Carnelians  in  form  of  fhells,    from  the 
river  Tomm  in  Siberia. 

2.  A  gat  in"  form  of  wood.     Such  a  piece  is 
faid  to    be  in    the    collection    of   Count 
Teffin. 

3.^Gorai!oids  of  white  flint,  ( Millepora. ) 
4.  Wood  of  yellow  flint. 

C.  Extraneous  bodies  changed  into  clay.     Argillil* 
ceous  changes;  Larvtf  argttiaet** 

A.  Loofe  and  friable. 
i.  Of  porcelain  clay. 

a.  In  form  of  vegetables, 

A  piece  of  white  porcelain  clay  from  Ja 
pan,  with  all  the  marks  of  the  root  of  a 
tree,  has  been  obferved  in  a  certain  collec 
tion. 

B.  Indurated, 

l.  In  an  unknown  clay. 
a.  In  form  of  vegetables.     OJkocoHa.     It  is 
faid  to  be  changed  roots  of  the  poplar 
tree,  and  not  to  confift  of  any  calcareous 
fubftance. 

A  fort  of  foffile  ivory  is  faid  to  be 
found,  which  has  the  properties  of  a 
clay ;  but  it  is  doubtful  if  it  has  been  right 
ly  examined. 

II .   Saline  extraneous  bodies,  or  fuch  as  are  penetrated 
by  mineral  falts.     Corpora  pet  egnna  infallta.     Larva 
tnjalitte. 
A.  With  the  vitriol  of  iron. 

1.  Animals. 

a.  Human  bodies  have  been  twice  found  in 
the  mine  at  Falun  in  Dalarne  j  the  laft 
was  kept  a  good  many  years  in  a  glafs-cafe, 
but  began  at  laft  to  moulder  and  fill  to 
pieces. 

2.  Vegetables. 
a.  Turf,  an-4 

£.  Roots 


I  308  J 

i>.  Roots  of  trees. 

Th-.;fe  are  found  in  water  ftrong'y  im 
pregnated  with  vitriol.  They  do  not  burn 
\vith  a  flame,  but  only  like  coal  in  a  ilrcn.ij 
fire;  neither  do  they  decay  in  the  air. 

III.  Extraneous  bodies  penetrated  by  mineral  inflam 
mable  fubftances,  or  mineral  phlogftion. 

d.  Penetrated  by  the  fubftance  of  pit-coals. 

j.  Vegetables,  which  commonly  have  Bea-n  woods, 
or  appertaining  to  them. 
a.  Fully  faturated.     Gages,  Jet.  (See  p.  104. 
col.  2.)  The  jet  is  of  a  folid  fhining  texture. 
1.  Not  perfectly  faturated;  Mumia  vtgttaliiis. 
It  is  loofej  refembles  umber,  and  may  ufed 
as  fuch. 

J5.  Penetrated  by  rock-oil  or  afphaltuxn. 
i.  Vegetables. 
a.  Turf. 

The  Egyptian  mummies  cannot  have  any 

place  here,  fvnce  art  alone  is  the  occauort 

that  thofe  human  bodies  have  in  length  of 

time  been  penetrated  by  the  afphaltum,  in 

the  fame  manner  as  has  happened  naturally 

to  the  wood  in  pit  coal  ftrata.     See  Mu  M M  v. 

C.  Penetrated  by  fulphur  which  has  diflblved  iron, 

or  by  marcafite  and  pyrites.     Pyrite  impregnata. 

Petrifatla  pyritacta. 

i.  Animals. 

a.  Human. 

b.  Bivalves. 

c.  Univalves, 

d.  Infecls. 

IV.  Metals  inform  of  extraneous  bodies  i  Larva  me  - 
talUferrt. 

A.  Silver;  Larva  argentlfer<s . 
(i.)  Native. 

a.  On  the  furfaces  of  fliells. 
(2.)  Mineralifed  with  copper  and  fulphur. 

a.  Fahlertz, 


a.  Fahlertz,  or  grey  filver  ore  in  form  of  ears 
of  corn,  &c.  and  fuppofed  to  be  vegetables, 
are  found  in  argillaceous  Hate  at  Franken- 
berg    and  Tahlitceren  in  HefTe.     • 
JR.  Copper;  Larva  cupriferx. 
(i.)  Copper  in  form  of  calx. 

a.  In  form  of  animals,  or  of  parts  belonging  to 
them. 

i.  Ivory  and  other  bones  of  the  elephant. 
The  Turcois  or  Turquoife  ;  which  is  of 
a  bluiih  green  colour,  and  much  valued 
in  the  ea(t. 

At  Simore  in  Languedoc  bones  of  ani 
mals  are  dug,  which  during  the  calcina 
tion  afmme  a  blue  colour;  but  it  is  not 
probable  that  the  blue  colour  is  owing  to 
copper. 

(2.)  Mineraiifed  copper,  which  impregnates  ex 
traneous  bodies;  Cuprum  miner  a 'if alum  corpora 
peregf'ina  ingreflimi* 

A.  With  fulphur  and   iron.      The  yellow  or 
marcafittcal  copper  ore  that  impregnates. 
i.  Animals. 
a.   Shells. 
I.  In  form  of  fifn. 

i.  With  fulphur  and  filver.     Grey  filver  ore 
orfahlerts,  like  ears  of  corn,  from  the  flate- 
quaries  in  Heffe. 
C.  Changes  into  iron;  Larva  ferriftrx. 

(i.)   Iron  in  foim  cf  calx,  which  has  aflumed 
the  place  or  the  lhape  of  extraneous  bodies; 
Ferrum  calciforme  corpora  peregrina  IngreJJinn. 
a.  Loofe ;  JLarve  ocLracete. 
i.  Of  vegetables. 

Roots  of  trees,  from  the  lake  Langelma 
in  Finland.  See  the  afts  of  the  Swediih 
Academy  of  Sciences  for  the  year  1742. 

b.  Indu 


I.  Indurated;  Larvx  h<£tnatitic<e . 

i.  Of  vegetables. 

(2.)   Iron  mineralifed,  aiTuming  the  fliape  of  ex 
traneous  bodies. 

a.  Mineralifed  with  fulphur.  Marcaflte.     .Lrtr- 
•va  pyritacce. 

V.  Extraneous  bodies  decompofing,  or  in  a  way  of 
deftru&ion;    Corpora  percgrina    in   gradibus    deftruc- 
twnis  conjiderata.     Mould;   Humus.     Turf;   Turba. 
4*  From  animals.  Animal-mould;  Humus  animatis. 

1.  Shells.      Humus  concbaceus. 

2.  Mould  of  other    animals;   Humus  diver/orum 
animalium. 

JB.  Vegetable  mould ;  Humus  vegetabllis. 

1.  Turf;    Turla. 

u.  Solid,  arid  hardening  in  the  air;  Turbafolida 
aereindurefcens.  This  is  the  bed  of  the  kind 
to  be  ufed  for  fuel,  and  comes  neareft  to  the 
pit-coals.  It  often  contains  a  little  of  the 
vitriolic  acid. 

b.  Lamelated  turf;   Turla  foliata.     This  is  in 
the  firil  degree  of  deftru<ftion. 

2.  Mould  of  lakes;  Humns  lacuftrls.     This  is  a 
black  mould  which  is  edulcorated  by  water. 

3.  Black  mould;  Humus dter.     This  is  univerfally 
known,  and  covers  the  furface   of  that  loofe 
earth  in  which  vegetables  thrive  beft. 

Order  III.    VOLCANIC  PRODUCTS  (H) 

I.  SLAGS;   Scoria  vulcanonim. 

Slags  are  found  in  great  abundance  in  many  places 
of  the  world,  not  only  where  volcanoes  yet  exift, 


(H)  For  the  nature,  hiftnry,  theory,  &c.  of  volca 
noes,  fee  the  article  VOLCANO. 

but 
2 


but  likewise  where  no  fabterraneons  fire  is  now 
known:  Yet,  in  Mr  Cronftedt's  opinion,  they 
cannot  be  produced  but  by  means  of  fire.  Thefe 
are  not  properly  to  be  called  natural*  iince  they 
have  marks  of  violence,  and  of  the  laft  change 
that  mineral  bodies  can  fuffer  without  the  cie- 
ftrucYion  of  the  world:  nor  are:they  artificial,  ac 
cording  to  the  univerfally  received  meaning  of 
this  word.  We  cannot,  however,  avoid  giving 
them  a  place  here,  efpecially  after  having  ad 
mitted  the  petrifactions ;  and  (hall  therefore  ar 
range  the  principal  of  them,  according  to  their 
external  marks. 

A.  Iceland. agate;   Achates  ijlundicus  ntger. 

It  is  black,  folid,  and  of  a  glafly  texture;  but  in 
thin  pieces  it  is  greenifh  and  femitranfparent 
like  glafs-bottles,  which  contain  much  iron. 
The  mod  remarkable  circumftance  ?s,  that  fuch 
large  folid  mafles  are  found  of  it,  that  there  is 
no  poffibility  of  producing  the  like  in  any  glafs- 
houfe. 

It  is  found  in  Iceland,  and  in  the  ifland  of  A- 
fcenfion:  The  jewellers  employ  it  as  an  agate, 
though  it  is  too  foft  to  reiift  wear. 

B.  Rheniih  millftone;  Lapis  molaris  Rhenanus. 

Is  blackilh-grey,  porous,  and  perfectly  refembles 
a  fort  of  flag  produced  by  mount  Vefuvius.  A 
variety  of  lava,  according  to  Kirwan. 

C.  Pumice-ftcne;   Pumex. 

It  is  very  porous  and  bliilered,  in  confequence 
of  which  it  is  fpecifically  very  1'ght.  It  re 
fembles  that  frothy  flag  which  is  produced  in 
the  iron  furnaces. 

1.  White. 

2.  Black. 

The  colour  of  the    firfc  is  perhaps  faded  or 

bleached,  becaufe  the  fecond  kind  comes  in 

C  c  tljat 


C     3"     3 

that  ftate  from  the  laboratory  itfeTf,  viz.  the 
.  volcanoes. 
Pearl  flag;    Scoria  ec-vjlantes  glolulis    vitreis  con- 

glomeratls. 

It  is  compounded  of  white  and  greenilh    glafs 

particles,  which  feem  to  have  been  congluti- 

nated  while  yet  foft  or  in  fufion.     Found  on 

the  Ifle  of  Aicenfion. 

.  Sla^-fand  or    aihes;    Scoria  fuherulente,  clneres 


This  is  thrown  out  from  volcanoes  in  form  of 
larger  or  fmaller  grains.  It  may  perhaps  be 
the  principle  of  the  Terra  Puzzolana;  becaufe 
fiich  an  earth  is  faid  at  this  time  to  cover  the 
ruins  of  Herculaneum  near  Naples,  which  hi- 
ftory  informs  us  was  deftroyed  by  a  volcano 
during  an  earthquake 
II.  Lavas. 

JLava  has  been  generally  underftood  to  denote  the 
aggregate  xnafs  of  melted  matters  which  flow 
out  of  the  mouths,  or  burft  out  from  the  fides, 
of  burning  mountains.  According  to  Mr  Kir- 
wan,  however,  lavas  are  the  immediate  produce 
of  liquefaction  or  vitrification  by  the  volcanic 
fires,  and  "  fiiould  carefully  be  diftinguifhed 
from  the  fubfequent  productions  affected  by  the 
water  either  m  a  liquid  or  fluid  ftate,  which  ge 
nerally  is  ejected  at  the  fame  time."  Ar;d  of 
lavas,  fo  diftinguilhed,  he  defcribes  feveral  va 
rieties.  See  the  article  LAVA,  in  the  order  of 
the  alphabet;  where  the  nature,  origin,  kinds, 
and  phenomena  of  lavas,  are  copioufly  defcribed 
and  explained. 
ill.  Eafaltes. 

This  ion  of  ftone  was  by  Cronftedt,  in  the  firft 
edition  of  his  Mineralogy,  ranked  among  the 
garnet  earths,  and  confounded  with  the  ftioerls; 

an 


[    3-3     3 

aft  impropriety  which  was  pointed  out  by  BLT^ 
man  in  his  Sciagraphta,  feel.  120. — Mr  Kinvaa 
conliders  bafaltes  as  an  imperfect  lava,  and 
afcribes  its  origin  both  to  fire  and  water.  He 
defcribes  it  as  found,  either,  I.  In  opaque  tri. 
angular  or  polyangular  columns^  which  ii  the 
proper  bafaltes:  Or,  2.  In  amorphous  maffes 
of  different  magnitudes;  forming  folid  blocks, 
from  the  fmalleic  fize  to  that  of"  whole  mountains: 
which  kind  is  called  trapp.  See  the  detached 
article  BASALTES  (i);  where  its  fpecies  and  va 
rieties  are  particularly  defcribed,  and  different 
opinions  dated  concerning  its  formation.  See 
alfo  the  article  TRAP?. — Some  plaufible  argu 
ments  again-ft  the  volcanic  origin  of  bafaltes  will 
be  mentioned  in  the  courfe  of  "the  fubjoined_nojte 
(K),  extracted  from  WiUlamfj  Natural  Hrj$ory  -of 
the  Mineral  Kingdom. 


(i )  In  that  article,  p,  46.  col.  i .  1.  9.  dele  the  words, 
"  The  Englifh  miners  call  it  cockle,  the  German/'/W/," 
—P.  47.  col.  2. 1.  28.  for  "  a.  kind  of  marble,"  read 
**  a  volcanic  produflion."  The'Lapb  Lydiust  or  Touch- 
done,  mentioned  in  the  fame  paragraph,  fliould  have 
bew'n  fpecified  to  be  of  the  fort  called  Trafip. 

(K)  There  is  a  great  variety  of  bafaltes  in  Scotland, 
particularly  of  the  grey  kinds;  forne  of  which  are  ca 
pable  of  the  higheft  degree  of  polilh.  -  A  good  black 
kind  is  met  with  on  the  fouth  fide  of  Arthur's  Seat 
near  Edinburgh,  where  it  forms  a  fmooth  perpendi 
cular  rock,  with  feveral  of  the  columns  broken  oft, 
and  the  fufpended  pieces  threatening  to  full  down  up 
on- -the  paflengers  below.  This  ftone,  is  capable  of 
receiving  a  fine  poliih  ;  and,  in  the  opinion  of  Mr  Wil- 
liam^/Avbtrld  be  fit  for-all  forts'of  ornaments  -about 
fepwlchral  monument!-.  It  will  polifh  to  a  bright  and 
beautiful  black  which  will  be  unfading. 

C  c  2  '  There 


There  is  another  kind,  heavy  and  hard,  of  a  black, 
or  blackifti-grey  colour  ;  of  which  great  quantities  have 
keen  carried  from  the  Frith  of  Forth  to  pave  the  ftreets 
<of  London.  This,  for  the  moft  part,  is  coarfely  gra 
nulated  in  the  infide,  though  fometimes  the  grain  is 
pretty  fine.  Sometimes  it  is  bright  in  the  infide  when 
broken.  It  is  compofed  of  grains  of  quartz  and  ihirl 
of  different  fizes,  and  commonly  contains  fome  iron. 
It  always  appears  in  thick,  irregular,  beds,  fome  of 
•which  are  enorrnoully  thick;  and  feldom  or  never 
equally  fo  :  on  the  contrary,  where  it  is  found  upper- 
moil,  it  frequently  fwells  into  little  hills  of  various 
iizes.  Molt  of  the  fmall  iflands  in  the  Frith  of  Forth 
are  compofed  of  this  kind  of  ftone  ;  as  well  as  fome 
hills  in  the  neighbourhood  of  InverkeithiBg  and  of 
Edinburgh. 

The  known  characterise  of  the  bafaltes  is  to  form 
itfelf  into  balls,  columns,  and  other  regular  figures. 
The  columnar  kind  affumes  a  pentagonal,  hexagonal 
or  heptagonal  figure ;  but  quadrangular  columns  are 
net  common.  They  are  all  fmooth  o»  the  outfide,  arid 
lie  parallel  and  contiguous  to  one  another  ;  fometimes 
perpendicular,  fometimes  inclining,  in  proportion  to 
the  pofition  of  the  flratum  which  is  thus  divided:  If 
the  (Iraturn  lies  horizontal,  the  columns  are  perpen 
dicular  ;  if  inclining,"  the  pillars  alfo  incline  in  exaft 
proportion  to  the  declivity  of  the  Ilrata,  being  ahvays 
broken  right  acrofs  the  (tralum.  Some  are  of  one  piece 
from  top  to'  bottom  ;  others  divided  by  one  or  more 
joints  laid  upon  one  another,  which  form  a  column 
cf  feveral  parts.  The  reck  called  the  Giant's  Cavfeway 
in  Ireland  is  a  pretty  good  fpeciirien  of  the  jointed  co 
lumnar  bafaltes  :  but  there  is  a  more  beautiful  fpecies 
above  Hilihoufe  lime-quarry,  about  a  mile  fout.h  of 
Linlithgow  in  Scotland;  and  a  coarier  one  near  the 
toll-bar  north  fide  of  Queen's  Ferry,  and  feveral 
other  places  in  Fife.  la  fome  places  the  bafaltes  are 

formed 


E    S'5     I 


iormed  inio  magnificent  columns  of  great  length ;  and 
in  others  afford  an  afiemblage  of  {mall  and  beautiful 
pillars  refembling  a  range  of  balluftrades  or  organ 
pipes.  Some  of  the  columns  on  the  fouth  fide  of  Ar 
thur's  Seat  already  mentioned  are  very  long ;  and 
there  are  likewife  magnificent  columns  of  great  length 
in  the  ifland  of  Egg,  and  others  of  the  Hebrides. 
Thefe  columns,  when  broken,  are  frequently  of  a 
black,  or  blackifa  grey,  in  the  infide  ;  fame  ot  them 
being  compofed  of  fmall  grains,  which  gives  them  an 
uniform  and  fmooth  texture  ;  but  much  of  this  fpecies 
of  llone  has  larger  grains  in  its  compofition,  rough, 
lliarp,  and  unequal,  when  broken.  All  the  grains, 
houever,  are  fine,  hard,  and  bright;  and  the  ftone 
>n  general  is  capable  of  a  fine  polifh. 

The  other  fpecies  of  bafaltes  which  forms  itfelf  in 
to  diftinct  malTes,  aulimes  fometimes  a  quadrangular, 
fomatimes  an  oval*  globular,  or  indetermiaate  figure. 
They  are  found  of  all  (izes  from  the  frze  of  an  egg 
to  that  of  an  houfe :  but  though  they  differ  in  fhape 
from  the  columnar  bafaltes,  they  agree  in  almoft 
every  other  refpect ;  whence  Mr  Williams  thinks  that 
they  are  only  to  be  accounted  a  variety  of  the  co 
lumnar  kind.  It  is  common  to  fee  one  ftratum  of 
the  bafaltine  rocks  exhibiting,  in  one  place,  regular- 
pillars  or  globes  ;  and  near  thefe,  very  irregular  ones, 
differing  very  little  from  the  common  cutters  found 
in  all  rocks  ;  and  at  no  great  diftance,  the  fame  rock 
is  found  to  run  into  one  entire  mafs,  exhibiting  no 
tendency  to  be  broken  or  divided  into  any  columns 
whatever,  Of  this  the  rock  of  Arthur's  Seat  is  an 
inftance.  Some  of  thefe  or>ly  produce  folid  mafies  of 
different  figures  and  fixes ;  while  others  produce 
quantities  of  a  fofter,  friable,  ftony  matter,  of  the 
fame  quality  in  which  the  hard  ma/Tes  of  different 
figures  are  found  imbedded.  Pretty  good  fpecimens 
of  the  fecond  kind  or  variety  of  bafaltes  are  met  with 
C  c  3  on 


on  the  road-fide  between  Cramo-nd  bridge  and  the 
Queen's  Ferry,  and  in  feveral  other  places  in  the 
LtOthians  and  in  Fife. 

The  cruftated  bafaltes  are  of  two  kinds  ;  r.  Such  as 
have  the  crufts  more  dry  and  friable  than  the  internal 
parts ;  and,  2.  Such  as  are  dry  and  friable  throughout 
the  whole  rnafs. 

The  firft  of  thefe  has  not  only  a  cruft  of  the  fria 
ble  matter  adhering  to  it,  but  is  likewife  imbedded 
in  a  quantity  of  the  fame.  Our  author  has  feen  ma 
ny  quarries  of  this  kind  of  bafaltes  dug  tor  the  high 
roads,  in  which  the  quantity  of  foft  friable  matter 
greatly  exceeded  that  of  the  hard  matfes,  and  in 
which  incrufted  ftones  of  various  fizes  and  (hapes  ap 
peared.  In  fuch  quarries,  fome  of  the  largeft  mattes 
have  only  a  few  coats  of  penetrable  friable  matter, 
1  unrounding  a  nucleus  which  varies  in  fize,  but  is 
uniformly  hard  throughout ;  and  we  ihall  find  other 
yolks  in  the  fame  quarry  imbedded  in  the  fofter  mat 
ter,  which,  when  broken,  exhibit  a  neft  of  (tones  in 
cluding  one  another  like  the  feveral  coats  of  an  onion. 
Thefe  cruftated  ba&ltes  which  envelope  one  another 
are  a  curious  fpecies  of  ftone.  The  feveral  coats  of 
furronnding  matter  differ  nothing  in  quality  from  the 
ftones  contained  in  them,  and  fome  of  the  inner  crufts 
are  often  very  hard ;  but  the  nucleus  within,  though 
fmall,  is  always  the  hardeft.  The  decompofition  by 
the  weathering  ©f  the  fofter  matter  found  fnrround- 
ing  and  enveloping  tlae  harder  rnaifes  of  ftone  in  this 
and  the  fecond  fpecies  of  bafaltine  rocks,  has  pro 
duced  a  phenomenon  frequently  met  with  in  Great 
Britain,  especially  in  Scotland,  which  greatly  puzzles 
many.  It  is  very  common  in  low  grounds,  and  upon 
fome  moderate  eminences,  to  fee  a  prodigious  multi 
tude  of  ftones  of  all  fhapes  and  fizes,  very  hard,  and 
pretty  fmooth  on  the  outfide.  Thefe  ftones  are  fome- 
fo  numerous  and  large,  that  it  is  often  found 

imprao 


r  3*7 


impracticable  to  clear  a  field  of  them.  Where  tKofe 
(tones  are  a  fpecies  of  bafaltes,  which  they  commonly 
are,  and  of  the  fecond  i'pecies  of  bafaltes  defefibed 
above,  they  always  originate  from  a  decompoiiti.'n 
of  the  more  foft  or  friable  parts  of  thofe  rocks,  which 
moulder  or  fall  away,  and  leave  the  harder  (tones  de 
tached  and  fcattered  about,  and  the  decompofed  mat 
ter  dilTolves  by  degrees,  and  becomes  good  corn  mould. 
Here  Mr  Williams  takes  occaiion  to  conteit  the 
opinion  of  thofe  who  think  that  (tones  grow  or  vege 
tate  like  plaots.  He  owns  indeed  th^t  they  increase 
in  bulk :  but  this,  he  fays,  is  only  in  fuch  fituations 
as  are  favourable  for  an  accretion  of  matter  carried 
down  and  depoiited  by  the  water  ;  in  all  other  fitua 
tions  they  grow  lefs  and  lefs.  "  Others  (fays  he)  ima 
gine,  that  thefe  (tones  (on  which  this  extraneous  mat 
ter  has  been  depofited)  were  rolled  about ;  that  the 
afperites  and  fharp  angles  were  by  that  means  worn 
off;  and  that  they  were  all  at  laft  depofited  as  we  fee 
them,  by  the  waters  of  the  univerial  deluge  :  and, 
having  their  obtule  fides  and  angles,  as  if  they  had 
been  rounded  by  rolling  in  wa:er,  makes  thefe  gentle 
men  confident  that  they  are  right ;  and  if  we  did  not 
frequently  find  (tones  exactly  of  the  fame  figure,  fize, 
and  quality  in  the  rock,  it  would  be  very  difficult  to' 
overthrow  this  hypo-thefts.  I  have  taken  great  pains 
to  inveftigate  this  point,  having  frequently  examine^ 
circumftances  ;  and  never  failed  to  difcover  the  ftra- 
tum  of  rock  which  thofe  detached  (tones  originally  be 
longed  to.  "  The  ftrata  or  beds  of  the  feveral  fpectes 
of  bafaltes  f-read  as  wide,  and  (tretch  as  far,  as  the 
ovher  concomitant  (trata  in  the  neighbourhood  where 
they  are  found  :  but  they  often  lie  very  flat,  or  with  a- 
moderate  degree  of  declivity  ;  and  consequently,  when 
the  fofter  and  more  friable  matter  found  in  the  inter- 
itices  of  thefe  rocks,  which  inclofes  and  binds  the  har 
der  rnaffes  in  their  Dative  beds,  is  decompofed,  the 

harder 


E 


harder  ftones  mud  then  lie  fcattered  wide  upon  the 
face  of  the  ground." 

The  fecond  fpecies  of  the  cruftated  bafaltes,  viz. 
that  which  is  dry  and  friable  throughout  the  whole 
inafs,  is  generally  .;f  a  coarfe  and  granulated  texture, 
and  of  ail  the  various  (hades  of  grey  colours  ;  from 
a  rufty  black  to  a  light-coloured  grey.  This  kind  of 
crurtated  bafaltes  is  developed  when  the  maffes  are 
either  broken  or  in  a  ftate  of  decompofition ;  and  there 
are  maffes  of  it  of  all  fizes  and  (hapes  found  in  the 
rocks,  refembling  the  fecond  and  third  fpecies  of  the 
bafaltes  ;  appearing  alike  fmcoth  on  the  outfide,  with 
obtuie  angles  ;  in  fhort,  refembling  the  bafaltes  in 
every  refpect :  but  when  they  are  expofed  to  the  ex 
ternal  air  and  weather  for  any  confiderable  time,  the 
feveral  incruftations  decay,  decompofe,  and  crumble 
down  by  degrees.  When  they  quarry  this  fpecies  of 
bafaltes  for  the  roads,  they  are  able  to  break  and  pound 
them  fmall  with  eafe ;  but  the  harder  fptcies  are  fo 
hard  and  cchefive,  that  they,  are  with  the  greateft  dif 
ficulty  broken  into  fufficiently  fmall  parts, 

Compofite  bafaltes  refembles  the  three  laft  fpecies, 
in  figure,  colour,  and  all  other  external  appearances ; 
being  diftinguifhable  from  them  only  in  the  internal 
ftructure  or  grain  of  the  (lone.  It  refembles  fome  of 
the  granites,  as  confiding  of  much  larger  grains  than 
the  other  bafaltes.  Many  of  the  larger  grains  in  the 
compofite  bafaltes  are  more  than  an  eighth  part  of  an 
inch  over,  and  fome  more  than  a  fourth  ;  appearing 
with  fmooth  flat  furfaces,  and  of  a  tabulated  texture, 
exactly  refembling  the  quartzy  grains  fo  commonly 
found  in  the  compofition  of  rnoft  of  the  granites.  The 
chief,  if  not  the  only,  diftinguifhable  difference  be 
tween  the  grains  in  each  of  them  is  the  colour.  They 
are  evidently  large  grains  of  quartz,  &.c.  which  exhibit 
flat  filling  furfaces  in  both.  Thofe  grains  or  frag 
ments  are  coznmonly  white,  yellowift,  red,  or  black, 
2  in 


in  the  compofitiqn  of  mod  .of  the  granites ;  whereas 
they  are  often  feen  of  a  pale  blue,  or  a  bluilh  grey 
colour,  in  the  composite  bafaltes,  and  fome  of  them 
approaching  to  white.  It  is  only  in  the  internal  ftruc- 
ture,  however,  that  thefe  bafaltes  have  any  refem- 
blances  to  the  granites ;  in  all  the  external  characters, 
they  differ  nothing  from  the  reft  of  their  own  genus. 

A  fifth  fpecies  of  bafaltes  is  indurated  through  the 
xvhole  ftra.turn,folid  and  uniform  through  all  its  parts, 
and  exhibiting  only  fuch  cracks  and  fiflures  or  cutters 
as  are  commonly  met  with  in  other  hard  beds  of  ilones. 
Many  beds  of  this  fpecies  are  frequently  met  with  in 
the  coal-fields,  and  the  miners  are  often  obliged  to 
fink  through  them  in  their  coal-pits.  "  The  Salii- 
bury  craig's  at  Edinburgh  (fays  our  author)  might 
be  fingled  out  as  a  good  example  of  this  fpecies  of 
ftone,  were  it  not  that  part  of  the  fame  ftratum  is 
formed  into  columns  on  Arthur's  feat ;  though,  I  be 
lieve,  this  is  no  good  exception,  as  it  evidently  ap 
pears  that  the  beds  of  bafaltes  which  are  formed  into 
columns,  globes,  &c.  only  alfume  thefe  figures  where 
they  are  expofed  to  the  influence  of  the  external  air, 
or  have  but  little  cover  of  rock  above  them.  When 
any  of  thofe  beds  ftrike  deep  under  the  cover  of  feveral 
other  ftrata,  they  are  not  found  in  columns,  Sec.  No 
thing  but  an  uniform  mafs  then  appears,  although  the 
fame  bed  is  regularly  formed  near  the  furface  ;  which 
proves  that  the  columnar  and  other  b:i(altes  are  formecl 
by  {link king  and  chapping. 

"  THe  ftrata  of  bafaltes  fpread  as  wide,  and  ftretch 
as  far  in  the  longitudinal  bearing,  as  the  other  differ 
ent  ftrata  which  accompany  them  in  the  countries 
where  they  are  found.  The  rocks  of  bafaltes  alfo  are. 
generally  found  in  very  thick  Grata  $  and  that  gene 
rally  in  places  where  no  other  rock  is  found  above 
the  bafaltes,  the  ftrata  of  it  are  often  very  unequal  in 
thicknefs.  But  this,  in  general,  is  only  in  filiations 

where 


C    320    ] 


where  no  other  rock  is  found  above  it ;  for  when  it 
fairly  enters  into  the  furface  of  the  earth,  fo  as  to 
have  other  regular  ftrata  above  it,  which  is  feen  in  an 
hundred  places  in  the  Lcthians,  "Fife,  and  other  parts 
of  Scotland,  it  then  appears  pretty  equal  in  thicknels, 
as  equal  as  moft  other  beds  of  fuch  great  thickneis 
are  ;  and  yet  it  is  remarkable,  that  although  moft  of 
the  ftrata  of  bafaltes  are  of  great  thicknefs,  there  are 
frequently  thin  ftrata  of  various  kinds  found  both 
above  and  below  it.  We  have  numerous  examples 
of  this  in  all  the  parts  of  Scotland  where  bafaltes  is 
found;  as  for  inftance,  there  are  thin  and  regular 
ftrata  feen  and  quarried  both  above  and  below  the 
thick  bed  of  that  rock  in  the  Salisbury  craigs  near 
Edinburgh.  In  the  Bathgate  hills,  fouth  of  Linlith- 
gow,  and  many  other  parts  of  Scotland,  tfcere  are 
ieveral  ftrata  of  bafaltes,  and  likewi.e  of  coal,  lime- 
{lone,  freeftone,  and  other  concomitants  of  coal  blend 
ed  promikuouftyjfratumjufirjtratunt  ;  and  the  bafalt 
is  frequently  found  immediately  above,  and  immedi 
ately  below  regular  ftrata  of  coal ;  of  courfe  bafaltes 
is  not  the  lava  of  volcanoes.  We  can  prove  to  occular  de- 
monftration,  from  the  component  parts,  and  from  the 
fituation,  ftretch,  and  bearing  of  the  ftrata  of  bafaltes, 
that  they  are  real  beds  of  ftone,  coeval  with  all  the 
other  flrata  which  accompany  them  ;  and  are  blended 
with  them  in  the  ftruclure  of  that  part  of  the  globe 
where  they  are  found,  as  they  dip  and  ftretch  as  far 
every  way  as  the  other  itrata  found  above  and  below 
them.  If  bafaltes,  therefore,  be  a  volcanic  production, 
the  other  ftra'a  muft  of  neceffity  be  fo  likewife.  But 
how  volcanoes  fhould  produce  coal,  and  how  that  coal 
fhould  come  into  contact  with  burning  lava,  is  not  a. 
little  problematical :  or  rather  it  is  ftrangely  abfurd  to 
imagine  that  burning  lava  can  come  into  contact  with 
ceal  without  deftroyino-  it. 

The 


The  regularly  ftratified  quartzy  white-mountain 
rock  is  fcarce  or  rather  not  to  be  found  in  moft  parts 
of  Britain.  In  the  Highlands,  however,  it  is  very 
common ;  and  in  fome  places  of  them  Mr  Williams 
has  feen  it  ftratifled  as  regularly  as  any  of  the  fand- 
ftoncs,  with  other  regular  ftrata  of  different  qualities 
immediately  above  and  below  it ;  and  fometimes  com- 
pofmg  large  and  high  mountains  entirely  of  its  own 
ftrata.  This  (tone  is  exceedingly  hard,  dry,  and  brit 
tle,  lull  of  crack^  and  (harp  angles  ;  the  different  ftrata 
fometimes  moderately  folid,  but  oiten  naturally  broken 
into  fmall  irregular  maffes,  with  angles  as  fharp  as 
broken  glafs,  av:dof  an  uniformly  fine  and  granulated 
texture,  reiembiing  the  fineft  iugar-loaf.  There  are 
large  and  high  mountains  of  this  ftone  in  Rofsfhire 
nnd  Invernefsfhire,  which,  in  a  clear  day,  appear  at  a' 
diftance  as  white  as  fnow,  without  any  lort  of  vegeta-r 
tion  on  them  except  a  little  dry  heath  round  the  edge 
of  the  hill. 


END  OF  MINERALOGY- 


METALLURGY 


ETALLURGY,  according  to  Boerhaavr, 
comprehends  the  whole  art  of  working  metals,  from 
the  glebe  or  ore,  to  the  uteniil ;  in  which  fenfe  efl ay- 
ing,  fmelting,  refining,  parting,  fmithery,  gilding, 
&c.  are  only  branches  of  metallurgy.  But,  in  the 
prefent  work,  Gilding,  Parting,  Purifying,  Refining, 
Smithery,  &c.  are  treated  under  their  proper  names. 
With  others,  therefore,  we  have  chofen  to  reftrain 
Metallurgy  to  thofe  operations  required  to  feparate 
metals  from  their  ores  for  the  ufes  of  life.  Thefe  opera 
tions  are  of  two  kinds :  the  fmaller,  or  Eflaying  ;  and 
the  larger,  or  Smelting.  But  a  particular  defcrip- 
tion  of  the  ores  themfelves  fcemed  likewife  neceflary 
to  be  given  ;  and  to  this  place,  tot ,  we  have  refer 
red  a  general  account  of  metals,  metallifation,  mines, 
and  ores,  as  a  proper  introduction  to  the  fubject. 
Hence  the  following  divifion  into  three  parts.  The 
Jirjl  treating,  I.  Of  metals  and  metallifation.  2.  Of 
mines  and  ores  in  general.  3.  Of  the  pyritec.  4.  Of 
the  eflaying  of  ores  in  general.  Thefecom/,  Of  the  par 
ticular  ores,  and  the  methods  of  eflaying  them.  The 
tfxref,  Of  fmelting  of  ores,  or  the  methods  of  extracting 
metals  from  large  quantities  of  ores  for  the  purpofes 
of  commerce  or  manufacture. 

D  d  PART 


£    3*4    3 

PART       L 


SECTION     I. 

Of  Metals  and  Metattifaihn. 

NDER  the  general  name  metal,  we  compre- 
bend  here  not  only  the  metals  properly  fo  called,  but 
alfo  the  femimeta/s,  or  all  mvitters  which  have  the  ef- 
fential  metallic  properties  which  we  fhall  here  recount. 
Thus  the  word  metal  and  metallic  juljlance  will  be  fy- 
nonymous  in  this  article. 

Metallic  fubftances  form  a  clafs  of  bodies,  not  very 
numerous,  of  very  great  importance  in  chemiflry,  me 
dicine,  arts,  and  the  ordinary  affairs  of  life.  Thefe 
fubftances  have  very  peculiar  properties,  by  which 
they  differ  from  all  other  bodies. 

The  natural  bodies  from  which  metals  differ  the  lead 
are,  earthy  and  pyritous  matters,  on  account  of  their 
folidity  and  denfity.  Metals  and  ftones  are,  neverthe- 
lefs,  very  different  ;  the  heavieft  ftones  which  are  un- 
metalltc  being  much  lighter  than  the  lighted  metals. 
A  cubic  foot  of  r.*.rble  weighs  252  pounds;  and  an 
equal  bulk  of  tin,  the  lighted  of  metals,  weighs  516 
pounds.  The  difference  is  much  greater  when  the 
weight  of  fuch  done  is  compared  with  that  of  gold, 
.a  cu'ric  foot  of  which  is  1326  pounds. 

Opacity  is  another  quality  which  metals  poffefs  emi 
nently,  the  opacity  of  metals  being  much  greater  than 
that  of  any  unmetailic  fubftance. 

This  great  opacity  of  metals  is  a  confequence  of  their 
denfity  ;  and  thefe  two  properties  produce  a  third,  pe 
culiar  alfo  to  metals,  namely,  a  capacity  of  reflecting 

much 


C    3*5    3 

ttiuch  more  light  than  any  other  body  :  hence  metals 
whofe  furfaces  are  polifhecl,  form  mirrors  reprefenting 
the  images  of  bodies  more  clearly  than  any  other 
matter.  Thus  looking-glaifes  produce  their  reflection 
merely  by  the  lllvering,  which  is  a  covering  of 
metal  upon  their  furfaces.  To  this  reflexive  proper 
ty  metals  owe  their  peculiar  luftre,  called  the  metallic 
luftre. 

Although  the  feveral  metallic  fubftances  differ  con- 
fiderably  in^hardnefs  and  fufibiHty,  we  may  fay  in  ge 
neral,  that  they  are  lefs  hard  and  kfs  fufible  than  pure 
earths* 

Metals  cannot  unite  with  any  earthy  fubftance,  not 
even  with  their  own  earths,  when  thefe  are  deprived 
of  their  metallic  itate  :  hence,  when  they  are  melted, 
they  naturally  run  into  globes,  as  much  as  the  abfo- 
lute  gravity  of  their  maf§>  and  their  prdTure  upon  the 
containing  vdFels,  Vfill  allow.  Accordingly,  the  fur- 
fkee  of  a  metal  in  fufion  is  always  convex.  A  metul  in 
that  ftate  always  endeavours  to  acquire  afpheiiealfonn, 
which  it  does  more  perfectly  as  the  mafs  is  leis.  This 
effect  is  very  fenfiV;le  in  quickfilver,  which  is  nothing 
but  a  metal  habitually  fluid  or  fufed.  A  mafs  of  feve 
ral  pounds  of  mercury,  contained  in  a  {hallow  wide- 
mouthed  veflel,  is  fo  fprcad  out,  that  its  upper  furfacc 
is  almoft  flat,  and  the  convexity  is  not  very  fenlible 
but  at  its  circumference  ;  on  the  contrary,  if  we  put 
very  fmall  maiTes  of  mercury  into  the  fame  veifel,  as, 
for  inftance,  maffes  weighing  a  grain  each,  they  be 
come  fo  round  as  to  feem  perfect  globes.  This  effect 
is  partly  occafioned  by  the  inaptitude  of  metals  to  unite 
with  the  velieis  containing  them  when  in  fufion,  by 
which  quality  the  whole  affinity  which  fubfifts  betwixt 
the  integrant  parts  of  thefe  metals  is  capable  of  acting  ; 
and  partly  allo  by  this  affinity,  which  difpofes  the  ir> 
teg  ant  parts  to  con.e  as  near  to  each  other  as  they 
can,  and  confequently  to  form  a  iphere. 

D  d  2  This 


C    3*6    3 

This  property  is  not  peculiar  to  melted  metals,  but 
to  all  fluids,  when  contiguous  to  bodies,  folid  or  fluid, 
with  which  they  have  no  tendency  to  unite.  Thus, 
for  initance,  mailes  of  water  upon  oily  bodies,  or  oily 
iriailes  upm  bodies  muiftened  with  water,  aflume  al- 
w&ys  a  fVrm  fu  much  nearer  to  the  fpherical  as  they 
are  fmaller.  Even  a  large  drop  of  oil  poured  upon  a 
watery  liquor,  fo  that  it  ihall  be  furrounded  with  this 
liquor,  becomes  a  perfect  iphere. 

All  metals  are  in  general  f<  luble  by  all  acids;  but 
often  thefe  ft,lutions  require  particular  treatment  and 
circnmflances,  which  are  mentioned  under  CHEMISTRY, 
With  acid's  they  form  a  kind  of  neutral  falts,  which 
have  all  more  cr  lefs  caufticity.  The  affinity  of  me 
tals  is  lefs  than  of  abforbent  earths  and  alkaline  falts 
to  acids  ;  and  therefore  any  metal  may  be  feparated 
from  any  acid  by  thefe  fubftances. 

Alkaline  falts  are  capable  of  ading  upon  all  metal 
lic  fubftances,  and  by  proper  management  will  keep 
them  diffolved. 

Metals  may  in  general  be  united  with  fulphur  and 
liver  of  iulphur.  With  fulphur  they  form  compounds 
lefemblsng  the  peculiar  fubltance  of  ores,  which  are 
generally  nothing  elfe  than  natural  combinations  of 
fulphur  and  metal.  Metals  have  lefs  affinity  with  ful 
phur  than  with  acids ;  hence  fulphur  may  be  fepara- 
ed  from  them  by  acids.  Some  exceptions  from  thefe 
general  rules,  concerning  the  affinity  ©f  metals  to  ful 
phur  and  liver  of  fulphur,  and  concerning  their  fepa- 
ration  from  fulphur  by  acids,  may  be  feen  under  thg 
articles  of  the  feveral  metals.  But  thefe  exceptions  do 
probably  take  place,  only  becaufe  we  have  not  yet 
found  the  method  of  furmpunting  fome  obftacles 
which  occur  in  the  ordinary  methods  of  treating  cer 
tain  metals. 

All  metals  may  in  general  be  united  with  each  o- 
ther,  with  which  they  form  different  allays  which  have 

peculiar 


peculiar  properties  ;  but  this  rule  alfo  is  not  without 
fome  exceptions. 

Metals  have  a  ftrong  affinity  with  the  inflammable 
pri  :-.:  p!c,  and  are  capable  of  receiving  it  fuperabun- 
dantly. 

LaCtly,  oily  fubftances  feem  to  be  capable  of  acting 
upon  all  metals.  Some  metals  are  eafily  and  copiouf- 
ly  diil"  Ived  by  oils  ;  and  perhaps  they  might  all  be 
found  to  be  entirely  foltife^e  in  oils,  if  the  methods 
known  in  chtmiflry  were  tried  for  the  accomplishment 
of  theie  folutions. 

The  properties  abovementioned  agree  in  general  to 
all  metallic  fubftances  :  but,  befides  the  properties  pe 
culiar  to  each  meta-,  feme  properties  are  common  to 
a  certain  number  of  them  ;  and  hence  they  have  been 
divided  into  feverul  clafles. 

Thofe  metallic  matters  which,  when  ftruck  by  a 
hammer,  ar  lirongly  ccmpreffcd,  are  extended,  length 
ened,  and  flattened,  without  being  broken  (which 
property  is  called  duSiHty  or  malleability)^  and  which 
alio  remain  fixed  in  the  mod  violent  and  long  conti 
nued  fire,  without  diminution  of  weight^  or  other  fen- 
fible  alteration,  are  called perfeft  metais.  Thefe  perfect 
metals  are  three  ;  gold,  Jilver,  platlna. 

The  metallic  matter^  which  are  ductile  and  fixed  in 
the  fire  to  a  certain  degree,  but  which  are  dellroyed 
by  the  continued  a-tion  of  fire,  that  is,  changed  into 
an  earth  deprived  of  all  the  character] ftic  properties  of 
metals,  are  called  imperfitt  metals*  Of  this  kind  are 
_£our  ;  copper t  irony  tin,  lead. 

The  metallic  fubttances  which,  as  well  as  the  im 
perfect  metals,  lofe  their  metallic  properties  by  expo- 
fure  to  fire,  but  which  alfo  have  no  ductility  or  fixity^ 
are  diftinguifhed  from  the  others  by  the  name  ofjemi-. 
metals.  Of  this  clafs  are  feven  ;  rcgulus  of  antimonyy 
bijmuth)  zinc9  nickel,  regulus  of  cobalt,  regulus  of  arfcnic^, 
and  of  manganefe* 

D  d  3  Laftl7> 


C    3*8    ] 

Laftly,  mercury,  which  has  all  the  general  proper 
ties  of  metals,  makes  aclafs  feparatefrom  the  others  ; 
becaufe  in  punty  and  gravity  it  is  fimilar  to  the  per- 
fe£l  metals,  and  in  volatility  to  the  femi  metals.  Its 
fufibility  alfofo  far  furpafTes  that  of  any  other  metallic 
matter,  that  it  is  fufficient  to  diftinguifh  it  from 
all,  and  to  give  it  a  diftincl:  clafs.  We  have  enume 
rated,  therefore,  in  all,  15  metallic  fubftances;  four 
of  which  were  unknown  to  the  ancients,  namely,  pla- 
tina,  regulus  of  cobalt,  of  manganefe,  and  nickel. 

As  chemifts  can  compound  bodies  by  being  capable 
of  feparating  the  principles  of  fuch  bodies,  and  even 
of  reuniting  their  principles  fo  as  to  reproduce  fuch 
compounds  as  they  were  originally ;  and  as  hitherto 
they  have  not  been  able  to  accomplish  any  fuch  decom- 
pofition  upon  the  perfect  metals :  hence,  if  all  the  other 
metallic  fubftances  were  equally  unalterable,-  we  fhould 
be  very  far  from  having  certain  notions  concerning 
metals  in  general:  but  if  we  except  gold,  filver,  and 
platina,  all  the  other  metallic  matters  are  fufceptible 
of  decompoiition  and  of  recompofition,  at  leaft  to  a 
certain  decree*;  and  experiments  of  this  kind  have 
thrown  much  light  on  the  fubjedl. 

We  maiy  obferve,  that  even  if  we  had  not  been  able 
to  decompofe  any  metallic  fubftance,  we  might  ft  ill, 
by  reflecting  on  the  eflfential  properties  of  metals, 
difcover  fufficiently  well  the  nature  of  their  princi 
ples. 

The  folidity,  the  confidence,  and  efpecially  the  gra 
vity,  which  they  poffefs  in  a  degree  fo  fuperior  to  all- 
other  bodies,  wottld  not  have  allowed  us  to  doubt  that 
the  earthy  element,  of  which  thefe  are  the  characlerif- 
tical  properties,  enters  largely  into  their  compofition, 
and  makes  their  bafis. 

The  facility  with  which  they  combine  with  almoft 
all  inflammable  matters,  and  with  all  thofe  which  have 
great  affinity  with  phlogifton,  fuch  as  acids  ;  joined  to 
their  incapacity  of  being  allayed  with  meagre  matters 

that 


C    3*9     1 

that  are  purely  earthy  or  purely  watery,  wkich  have 
no  dif petition  to  unite  with  phlogiiton  ;  would  alfb  have 
furniihed  very  iironger  motives  to  believe,  that  the  in 
flammable  principle  enters  largely  into  the  compofition. 
of  metals. 

The  deftruftible  metals  prefent  exa&ly  the  fame 
phenomena  as  all  other  bodies  containing  the  inflam 
mable  principle  do,  in  the  ftate  of  combustion.  When 
expoled  to  fire,  without  accefs  of  air,  that  is,  in  clofe 
velfels,  they  become  red-hot,  melt,  or  fublime,  ac 
cording  to  their  nature  :  but  they  receive  no  alteration 
in  their  compofition  from  fire  applied  in  this  manner, 
and  they  are  afterwards  found  to  be  exactly  in  the  fame 
{late  as  before.  In  this  refpetf,  they  refemble  periedt- 
ly  all  bodies  which  contain  no  other  inflammable  mat 
ter  than  pure  phlogifton. 

But  when  imper'ecl:  metals  are  expofed  to  fire,  with 
accefs  of  air,  as,  for  inftance,  under  a  inurHe  in  a  fur 
nace  which  is  made  very  hot,  then  they  burn  more  or 
lefs  fettfibly,  as  their  inflammable  principle  is  more  or 
lefs  abundant,  or  more  or  lefs  combined.  Some  o£ 
th-em,  as  iron  and  zinc,  burn  with  a  very  lively  and 
brilliant  flame  ;  but  this  flame  is  of  the  fame  nature  as 
that  of  charcoal,  offulphur,  of  all  bodies,  the  comb u- 
ftible  principle  of  which  is  pure  phlogiilon,  and  is  not 
in  an  oily  itate,  that  is,  furniihes  no  foot  capable  of 
blackening. 

The  imperfect  metals  detonate  with  nitre,  and  their 
phlogift  n  is  coniumed  by  this  method  much  more 
quickly  and  completely  than  by  ordinary  calcination 
orcombuftion.  Their  flame  is  alfo  much  more  lively 
and  brilliant ;  and  £  me  of  them,  as  iron  and  zinc,  are 
ufecl  in  compofitio-ns  for  fireworks  from  their  very 
vivid  and  beautiful  flame. 

Nitre  is  alkaiifed  by  thefe  metallic  detonations  ex 
actly  in  the  fame  manner  as  in  its  detonation  by 
coals. 

Laftly, 


C    33°    3 

Laftly,  imperfecl:  metals  being  treated  with  acids 
which  have  an  affinity  whh  plogillon,  that  is  \vith  the 
vitriolic  and  nitrous  acidt.,  and  deprived  by  the'e  acids 
of  a  more  or  lefs  confiderable  part  ot  their  inrlarnrna-' 
b!e  principle  ;  they  give  a  fulph'ireous  quality  to  vi 
triolic  acid,  and  are  even  capable  of  producing  fulphur 
with  that  acid. 

Although  the  experiments  now  mentioned  were  the 
only  proofs  of  the  exillenre  of  an  ir  flammable  principle 
in  metallic  Jubilances,  they  will.:  ;^e  fufficient  to 
eftablifli  it  inconteftably.  But  we  1l'  ill  lee,  when  we 
continue  to  examine  the  phenomena  attending  the  de- 
compofition  of  metals,  that  thofe  are  not  the  only 
proofs. 

If  the  inflammable  matter  which  fliows  itfelf  fo  evi 
dently  in  the  burning  of  metals,  is  really  one  of  their 
ccnilitucnt  parts,  th  ii  efTential  prope.  t:es  mult  be  al 
tered  in  propoitiun  to  the  quantity  of  it  taken  from 
them:  and  this  evidently  happens  up  n  trial,  for  the 
refiduum  (  f  metallic  matters,  alter  calcination,  departs 
from  the  metallic  c^a>  a«£ter,  and  approaches  to  the  na 
ture  of  mere  earth.  The  opacity,  brilliancy,  ductility, 
gravity,  fufibility,  volatility,  in  a  W.-TCI,  all  the  pro 
perties  by  which  metallic  fubftances  :V*fi-;r  front  fimple 
earths,  diminiih  or  entirely  difiippear,  by  taking  frrm 
them  their  infl.immabl:  pri;  tijple  ;  fo  that  when  their 
caliina*i<  n  has  been  carried  as  far  as  is  pcffible,  they 
refemble  mere  earths,  and  have  no  1<  n^jer  a)-y  thi  in 
common  with  metals.  TKefe  earths  can  no  long  •  -»e 
combined  with  acids  (^r  with  metals,  Vut  are  capable 
ef  uniting  with  ppre  earths.  Thev  are  then  ca.  ed 
falxes  or  metallic  earths.  See  CHEMISTRY. 

We  muft  obferve  concerning  the  decompaction  of 
metals,  i  Tl;at  when  a  fnull  qii'-rntivy  of  inflammable 
principle  is  taken  from  n  Ual,  (  nly  a  fmall  quantity 
of  calx  is  formed,  and  the  remaning  part  continues  in 
the  metallic  ftate  :  hence,  as  the  portion  of  calcined 
matter  can  no  longer  remain  united  with  that  which 


C     33'     3 

is  deftroyed,  it  feparates  in  form  of  fca'es  from  the 
furface  of  the  metal,  when  the  calcination  has  been 
performed  without  fulion,  as  general. y  happens  to  iron 
and  to  copper  :  or  thefe  fcales  float  upon  the  furface 
of  the  melted  matter  when  the  calcination  is  perform 
ed  during  fulion,  becaufe  the  calx  is  fpecifically  light 
er  than  the  metal ;  as  happens  to  the  very  fulible  me 
tals,  as  tin,  lead,  and  moil  of  the  femimetals. 

2.  The  imperfect  metals  are  not  all  equally  eafily 
and  completely  calcinable.  In  general,  as  "much  of 
their  pblogifton  may  be  eafily  taken  from  them,  as  is 
fuiHcient  to  deprive  them  of  their  metallic  properties  ; 
but  the  remaining  portion  of  their  phlogifton  cannot 
be  fo  eafily  driven  off.  Some  of  them,  as  copper, 
refill  the  firft  calcination  more  than  the  reft:  and 
others,  as  lead  and  bifmuth,  may  be  very  eafily  calci 
ned,  but  only  to  a  certain  degree,  and  retain  always 
obftinately  the  laft  portions  of  their  inflammable  prin 
ciple  ;  laftly  others,  as  tin  and  regukis  of  antimony, 
may  not  only  be  eafily  and  quickly  calcined,  but  alfo 
much  more  completely.  All  the  other  metals  partake 
more  or  lefs  of  the  properties  relating  to  their  calci 
nation.  In  general,  if  \ve  except  the  labours  of  al- 
chemifts,  which  are  not  much  to  be  depended  upon, 
we  have  not  yet  made  all  the  proper  eiforts  to  arrive  at 
a  perfect  calcination  of  the  feveral  metallic  fubftances  ; 
which  however  is  abfolutely  neceffary,  before  we  can 
arrive  at  a  c<  mplete  knowledge  of  the  nature  of  their 
earths,  as  we  fhall  afterwards  fee. 

When  metallic  earths  have  loll  but  little  of  their 
phlogifton,  and  are  expofed  to  (Irong  fire,  they  melt, 
and  are  reduced  to  compact  maffes,  ftill  heavy  and 
opake  ;  although  much  lefs  fo  than  the  metals,  and  al 
ways  brittle  and  abfolutely  unmalleable.  If  the  calci 
nation  has  been  more  perfect,  the  metallic  earths  are 
ftill  fufible  by  fire,  but  lefs  eafily,  and  convertible  into 
brittle  and  trar.fparent  maffes  poffefled  of  all  the  pro 
perties  cf  glafs,  and  are  accordingly  called  meta-lk 

gla/v. 


t    33*    J 

Thefe  glaffes  do  not  pofTefs  any  of  the  proper 
ties  of  their  metals,  excepting  that  they  are  fpecifically 
heavier  than  other  glailes,  that  they  are  capable  of 
being  attacked  by  acids,  and  that  the  glaffes  of  the 
femimetals  are  fomewhat  lefs  fixed  than  unmetallic 
glaffe?.  LafUy,  when  the  calcination  of  metals  has 
been  carried  to  its  greateft  height,  their  earths  are  ab- 
folutely  fixed,  and  unfufible  in  the  fire  of  our  furnaces, 
and  poffefs  no  longer  the  Iblubility  in  acids  by  which 
metals  are  characlerifed* 

Thefe  are  the  principal  changes  which  metals  fufFer 
by  lofing  their  phlogifton.  They  are  thus  changed 
into  fubftances  which  have  no  properties  but  thofe  of 
earth.  This  is  a  certain  proof  that  the  inflammable 
principle  is  one  of  their  conftituent  parts.  But  we  have 
alfo  other  proofs  of  this  important  truth*  The  reduc 
tion  of  metallic  calxes  into  metal,  by  the  addition  of 
phlogifton  alone,  completes  the  preen  andthewhele 
forms  one  of  the  cleared  and  mod  f&tiifa&ory  demon* 
ftratlom  in  all  the  fciences,  Thii  reduction  is  eftec- 
ted  in  the  following  manner  t 

If  the  earth  of  a  metal  be  mixed  with  any  inflam 
mable  matter,  which  either  is  or  can  be  changed  into 
the  ftate  of  coal,  together  with  fome  fait  capable  of 
facilitating  fufion,  but  which,  from  its  quantity  or  qua 
lity,  is  incapable  of  receiving  the  inflammable  princi 
ple  ;  arid  if  the  wjiole  be  put  into  a  crucible,  and  the 
fufton  promoted  by  a  fire  gradually  railed;  then  an 
effervefcence  will  happen,  accompanied  with  a  hiding 
noife,  which  continues  a  certain  time,  during  which 
the  fire  is  not  to  be  increafed  ;  afterwards,  when  the 
whole  has  been  well  fufed,  and  the  crucible  taken  from 
the  fire  and  cooled,  we  fhall  find  at  the  bottom,  upon 
breaking  it,  the  metal,  the  earth  of  which  was  em 
ployed  for  the  operation,  poflefled  of  all  the  properties 
which  it  had  before  calcination  and  reduction. 
-  We  cannot  doubt  that  this  transformation  of  an 
earthy  fubftance  into  a  metal,  is  folely  caufed  by 

the 


C     333     ] 

phloqjifton  pafling  from  the  inflammable  matter  to 
the  metallic  earth.  For,  firft,  in  whatever  manner  and 
with  whatever  fubftance  metallic  earths  be  treated, 
they  cannot  be  ever  reduced  into  metals  without  a  con 
currence  of  fome  fubflance  containing  phlogillon. 
2dly,  The  nature  of  the  fubilance  which  is  to  fu  nilh 
phlogift.m  is  quite  indifferent,  becaufe  this  principle  is 
the  fame  in  all  bodies  containing  it.  3<ily,  If>  after 
the  operation,  the  fubftance  furnilliing  the  phlogiilon 
be  examined,  we  ihall  find  that  it  has  left  as  much  of 
that  principle  as  the  metallic  earth  has  received.  See 
PHLOGISTON. 

The  facts  related  concerning  the  decompofition  and 
the  recompofition  of  metals,  prove  inconteftably  that 
they  are  all  compofed  of  earth  and  phlogifton.  But 
we  do  not  yet  certainly  know  whether  thefe  two  be 
the  only  principles  of  metals.  We  might  affirm  this 
if  we  could  produce  metals  by  combining  phlogifton 
wirh  fome  matter  which  is  certainly  known  to  be  limple 
earth.  But  this  hitherto  has  not  been  accomplished  ; 
for  if  we  try  to  treat  any  earth,  which  has  never  been 
metallic,  with  inflammable  matters,  we  fhall  perceive 
that  the  fimple  earths  are  not  combinable  with  phlogi- 
fton  fo  as  to  form  metals.  We  mail  even  perceive  that 
the  metallic  earths  refill  this  combination,  and  are  in- 
capable  of  reduction  into  metal,  when  they  have  been 
fo  much  calcined  as  very  nearly  to  approximate  the  na 
ture  of  fimple  earths. 

Thefe  coniiderations,  added  to  this,  that  we  cannot 
eafily  conceive  ho^v,  from  only  two  certain  principles, 
fo  many  very  different  compounds  as  the  feveral  me 
tallic  fubftances  are,  fhould  refult,  are  capable  of  indu 
cing  a  belief  that  fome  other  principle  is  added  to  thefe 
two  already  mentioned  in  the  compofition  of  metals. 

Many  great  chemitts,  and  particularly  Becher  and 
Stahl,  feem  to  bs  of  this  opinion.  Chiefly  from  the 
experiments  concerning  the  mercurification  of  metals, 
they  believe  that  this  third  principle  exifts  copiouily 

in 


t     334    3 

in  mercury  ;  that  it  is  of  a  mercurial  nature  ;  that  it 
nlfo  exifts  in  marine  acid,  to  which  it  gives  its  fpecific 
character  ;  that,  by  extracting  this  mercurial  principle 
from  marine  acid,  rr  any  other  body  containing  it  co- 
pioufly,  and  by  combining  it  with  fimple  earths,  thefe 
may  acquire  a  metallic  character,  and  be  rendered  ca 
pable  of  receiving  phlogifton,  and  of  being  completely 
metallifed. 

Thefe  chemifts  admit  alfo,  and  with  probability,  a 
different  proportion  of  metallic  principles  in  the  feve- 
ral  metals  ;  ar.d  believe,  that  particularly  the  principle 
which  they  call  mercurial  earth,  exifts  more  copioufly 
and  fenfibly  in  certain  metals  than  in  others.  The  moll 
mercurial  metals,  according  to  them,  are  mercury,  fil- 
ver,  lead,  and  arfenic.  Moft  chemifts  diftinguifh  them 
from  the  other  metals,  which  they  call  white  metals, 
lur.ar  metals^  cr  mercurial  metals. 

AU  thefe  confiderations  being  united,  and  others  too 
many  to  be  mentioned,  give  fome  probability  to  the 
exiftence  of  the  mercurial  principle  in  metals.  We  muft 
however  acknowledge,  that  the  exiftence  of  this  prin 
ciple  is  meiely  probable  ;  and,  as  Stahl  obferves,  is 
n<?t  rearly  fo  well  demonftrated  as  that  of  the  inflam 
mable  principle  :  we  may  even  add,  that  wt  have  flrong 
motives  to  doubt  of  its  exiftence. 

To  produce  metals  artificially  has  juftly  been  reck 
oned  one  of  the  raoft  difficult  problems  in  chemiftry. 

Metallic  fubftances,  although  they  refemble  each 
other  by  their  general  properties,  differ  neverthelefs 
from  each  ether  very  evidently  by  che  properties  pe 
culiar  to  each.  Do  thefe  differences  proceed  from 
the  different  \  roportion,  and  from  the  more  or  his  in 
timate  connexion  cf  the  inflammable  principle  with 
the  earthy  principle,  fuppofing  that  this  latter  fhould 
be  effentially  the  fame  in  all  metals  ?  or  ought  they  to 
be  attributed  to  the  difference  of  earths,  which  in  that 
cafe  would  be  diftincl:  and  peculiar  to  each  metal  ?  or, 
laftly,  do  metals  differ  frcm  each  other,  both  by  the 
4  nature 


C     335     ] 

nature  of  their  earths,  and  by  the  proportion  and  in 
timacy  of  connection  of  their  principles  ?  All  thefe 
things  are  entirely  unknown  ;  and  we  may  eaiily  per 
ceive,  that  till  they  are  known,  we  cannot  difcover 
what  method  to  purfue  in  our  attempts  to  acccmpliili 
the  combinations  we  are  now  treating  of. 

The  moil  eilential  point  then  is,  to  arrive  at  a  know 
ledge  of  the  true  nature  of  the  earths  which  are  in  me 
tals  ;  and  the  only  method  of  arriving  at  this  know 
ledge  is,  by  reducing  them  to  their  greateft  (implicity 
by  a  perfect  calcination.  But  this  cannot  be  accom- 
plifhed  but  by  long  and  difficult  operations.  We  have 
feen  above,  that  all  metals  are  not  calcinable  with 
equal  eafe  ;  that  the  perfect  metals  have  not  been  hi 
therto  calcined  truly  by  any  procefs  ;  and  that,  in 
general,  the  iaft  portions  of'  phlogifton  adhere  very 
itrongly  to  calcinable-metals. 

Some  metals,  however,  -as  tin  and  regulus  of  an 
timony,  may  be  eafily  calcined  fo  as  to  be  rendered 
irreducible.  By  carrying  the  calcination  ftill  fur 
ther,  we  might  obtain  their  earths  fo  pure,  that  all 
their  eiTential  properties  may  be  difcovered,  by 
which  they  might  be  eafily  compared  together. 
This  comparifon  would  decide  whether  their  nature 
be  efTentially  different  or  not. 

If  they  vere  found  to  be  compofed  of  earths  effen- 
tially  the  fame,  we  might  next  proceed  to  compare  me 
tallic  with  unmetallic  earths.  If  the  former  were  found 
iimiliir  to  iome  of  the  latter  kind,  we  fhould  be  then 
allured  that  the  earth  of  metals  is  not  peculiar  to  them, 
and  that  ordinary  unmetallic  earths  are  fufceptible  of 
metallifation.  From  fome  late  experiments,  it  was 
imagined  that  lime  ard  mngnefia  alba  were  capable  of 
being  converted  into  n.etaliic  fubftances,  but  the  pro- 
ceifes  are  now  found  to  be  erroneous. 

The  greater  tl.c  i  i  n  her  of  metals  operated  upon, 

the  more  gener.  ertam  the  conferences  refiilt- 

ing  from  thefe  would  he  :   fo  that,  ilr  iailance,  if  the 

1C  e  operation 


C    336    ] 

operation  were  extended  to  all  calcinable  metals  ;  and 
if  the  refult  of  each  of  thefe  operations  were,  that  the 
calxes,  when  perfectly  dephlogifticated,  do  not  differ 
from  each  other,  and  are  fimilar  to  earths  already 
known  ;  we  might  conclude  from  analogy,  and  we 
Ihould  be  almoft  certain,,  that  the  earths  of  the  per 
fect  metals  are  alfo  of  the  fame  nature. 

They  who  know  the  extent  and  difficulties  of  che 
mical  operations,  will  eafily  perceive  that  this  would 
be  one  of  the  moft  confiderable.  Neverthelefs,  after 
having  determined  this  eflential  point,  we  fhould  only 
have  done  half  our  work  :  "For  a  knowledge  of  the 
nature  of  the  earth  of  metals,  and  where  it  is  to  be 
found,  would  not  be  fufiicient :  we  muft  further  en 
deavour  to  find  a  method  of  combining  with  this 
earth  a  fufficient  quantity  of  phlogtfton,  and  in  a 
manner  fufficiently  intimate,  that  a  metal  might  be 
formed  by  fdch  a  combination.  But  this  fecond 
difficulty  is  perhaps  greater  than  the  former. 

We  muft  obferve  here,  that  fome  famous  chemical 
procefles  have  been  confidered  by  many  as  metallifa- 
tions,  but  which  are  really  not  fo.  Such  is  Becher's 
famous  experiment  of  the  mln.ra  arenarla  perpettia, 
by  which  that  chemift  propofed  to  the  States  General 
to  extract  gold  from  any  kind  of  land.  Such  alfo  is 
the  procefs  of  Bcche.r  and.  of  Geolfroy,  to  obtain  iron 
from  all  clays  by  treating  them  with  linfeed  oil  in  cloie 
vefTels.  In  thefe,  and  many  other  fuch  precedes,  we 
only  obtain  metal  that  was  already  formed.  Every 
earth  and  land,  as  the  intelligent  and  judicious  Cra 
mer  obferves,  contains  fome  particles  .of  gold.  Clays 
Jo  not  commonly  contain  iron  ready  formed  ;  but  all 
of  them  contain  a  ferruginous  earth,  naturally  dif- 
pofed  to  metallifation.  (S,;e  CLAY.)  Accordingly  we 
mud  conclude,  that,  by  Mr  Geoffrey's  experiment, 
iron  is  only  reduced  or  revived,  but  is  not  produced. 

The  great  difficulties  which  occur  in  attempting  to 
give  a  metallic  quality  to  fimple  earths  have  induced 

•A  belief, 


.      C     337     J 

a  belief,  that  the  nature  of  metals  ready  formed 
might  be  more  eafily  changed,  and  the  lefs  perfect 
brought  to  a  more  perfect  date.  To  effect  this, 
Which  is  one  of  the  principal  objects  of  alchemy,  and 
is  called  tranf mutation^  numberlefs  trials  have  been 
made.  As  we  have  not  any  certain  knowledge  of 
what  occaiions  the  fpecific  differences  of  metallic  fub- 
ftances,  we  cannot  decide  whether  tranfmutation  be 
poifible  or  not.  In  fa&,  if  each  metallic  fubftance 
have  its  peculiar  earth,  efTentially  different  from  the 
earths  of  the  others,  and  consequently  if  the  differ 
ences  of  metals  proceed  from  the  differences  of  their 
earths;  then,  as  we  cannot  change  the  effential  pro 
perties  of  any  fimple  fubftance,  tranfmutation  of  metals 
niuft  be  impofT-ble.  But  if  the  earths  and  other  princi 
ples  of  metals  be  efTentially  the  fame,  if  they  be  combi 
ned  in  different  proportions  only,  and  more  or  lefs 
ftrictly  united,  and  if  this  be  the  only  caufe  of  the  fpe 
cific  difference  of  metals  j  we  then  fee  no  impoffibility 
in  their  tranfmutation. 

Whatever  be  the  caufe  of  the  differences  of  metals, 
their  tranfmutation  fet-ms  to  be  no  lefs  difficult  than 
the  production  of  a  new  metallic  fubftance  ;  and  per 
haps  it  is  even  more  difficult.  Alchernifts  believe  that 
tranfmutation  is  poffible,  and  they  even  affirm  that 
they  have  effected  it.  They  begin  by  fuppofmg  that 
all  metals  are  compofed  of  the  fame  principles  ;  and 
that  the  imperfect  metals  do  not  differ  from  gold  and 
filver,  but  becaufe  their  principles  are  not  fo  well 
combined,  or  becaufe  they  contain  heterogeneous  mat 
ters.  We  have  then  only  thefe  two  faults  to  remedy, 
which,  as  they  fay,  may  be  done  by  a  proper  coction, 
and  by  feparahng  the  pure  from  the  impure.  As  we 
have  but  very  vague  and  fuperficial  notions  concerning 
the  chafes  of  the  differences  of  metals,  we  confcfs  that 
we  cannot  make  any  reafonable  conjecture  upon  this 
matter ;  and  we  faall  only  advife  thofe  who  would 
E  e  2  proceed 


C    338    3 

proceed  upon  good  principles,  to  determine  previouily, 
if  metals  have  each  a  peculiar  earth,  or  only  one  com 
mon  to  them  all.  In  the  fecond  place,  if  it  fhould  be 
demrnftrated  that  the  earthy  principle  is  the  fame  in 
all  metals,  and  if  that  be  demonftrated  as  clearly  as 
the  identity  of  the  inflammable  principle  in  metals  is 
proved  ;  they  muft  then  determine  whether  chefe  two 
be  the  only  principles  in  metals,  whether  the  mercu 
rial  principle  exiits,  and  whether  it  be  efiential  to  all 
metals  or  to  feme  only,  and  what  is  the  proportion 
of  thofe  two  or  three  principles  in  the  feveral  metallic 
fubftances.  When  we  (hall  clearly  underftand  thefe 
principal  objects,  we  may  then  be  able  to  determine 
concerning  the  pofiibility  of  tranfmutation  ;  and  if  the 
poffibility  fhould  be  affirmed,  we  (hall. then  begin  to 
difcover  the  road  which  we  ought  to  purfue. 

We  have  no  reafon  to  believe  that  any  other  prin 
ciple  enters  into  the  ccmpofiticn  of  metals  than  thofe 
abovementioned  :  no  veftige  is  perceptible  of  either  air 
or  water.  Some  chemifts  have  neverthelefs  advanced 
that  they  contain  a  faline  principle.  If  that  were  true, 
they  would  alfo  contain  a  watery  principle.  But 
all  the  experiments  adduced  to  prove  this  opinion  are 
either  falfe,  or  only  fhow  the  prefence  of  fome  faline 
particles  extraneous  to  the  metals,  or  contained  un- 
knowa  to  the  chemifts  in  the  fubftances  employed  in 
the  experiments.  For  metals  perfectly  pure,  fu Reel 
ed  to  all  trials  with  fubftances  which  do  not  contain 
and  which  cannot  produce  any  thing  faline,  do  not 
difcover  any  faline  propeity.  We  muft  however 
except  arfenic,  and  even  its  regulus,  thefe  being  fm- 
gular  fubftances,  in  which  the  faline  are  as  fenfible  as 
the  metallic  properties. 

-  Arfenic  feems  to  be  one  of  thofe  intermediate  fub 
ftances  which  nature  has  placed  in  alnaofl  all  its  pro 
ductions  betwixt  two  different  kinds,  and  which  par 
take  of  the  properties  of  each  kind.  Arfenic  thus  placed 

betwixt 


C     339     .1 

betwixt  metallic  and  falir.e  fubttances  has  properties, 
common  to  both  thefe  kinds  of  fubflances,  without  be 
ing  either  entirely  a  metal  or  fait.  See  ARSENIC. 

As  water  feems  to  a6t  to  a  certain  degree  upon  iron, 
even  without  the  concurrence  of  air,  as  the  operation 
of  martial  ethiops  fliows,  we  might  thence  fufpect 
ibinething  faline  in  that  metal.  Nevertheless,  what 
happens  in  that  operation  has  not  been  fo  well  explain 
ed,  that  any  certain  confequences  can  be  deduced, 
i.  The  water  employed  ought  to  be  perfectly  pure; 
that  is,  diftilled  rain-water.  2.  The  iron  employed 
ought  alfo  to  be  perfectly  pure,  and  fuch  is  very  diffi 
cultly  to  be  procured.  3.  The  operation  ought  to  be 
performed  in  a  bottle  accurately  clofed,  that  we  may 
be  aifured  that  the  air  contributes  nothing  to  the  action 
upon  the  iron.  4.  After  the  water  has  remained  a 
long  time,  fuppofe  a  year,  upon  the  iroH,  it  ought 
to  be  carefully  filtrated  and  examined,  to  afcer- 
tain  whether  it  really  has  diifolved  any  part  cf  the 
metal. 

In  the  mean  time,  we  way  conclude  that  metals  do 
not  feem  to  contain  any  faline  principle.  And  when. 
\ve  confider  well  their  general  properties,  they  feem 
to  be  nothing  elfe  than  earths  combined  more  or  lefs 
intimately  with  a  large  quantity  of  phlogifton.  Al 
though  we  can  demoniirate  that  their  inflammable 
principle  is  not  in  an  oily  Hate,  and  that  it  is  pure 
phlogillon,  they  have  neverthelefs  an  oily  appearance, 
in  this  circuir.ftance,  that  they  adhere  no  more  than 
oils  to  earthy  and  aqueous  Jubilances  and  that  they 
always  aflame  a  globular  nVure  when  fupported  by 
thefe  fubftanc.es  entirely  free  from  phlogiuV'ii. 

This  refemblance  is  fo  fenfihle,  that  chemifts,  be 
fore  they  knew  the  nature  of  phlogiston,  believed  that 
metals  contained  an  oily  and  fat  nutter.  The  caufe 
of  this  quality  of  metals  is  th-i  quantity  of  pblogiiton 
which  they  contain.  Sulphur,  phofphorus,  oih,  and 
even  fats,  have  this  appearance  merely  from  the  in- 
li  e  3  flammable 


3 

flammable  principle  which  enters  into  their  competi 
tion:  for  this  pi  open  y  is  ccmn.unicated  by  that  prin 
ciple  to  every  compound  which  contains  a  certain 
quantity  of  it.  See  PHLOGISTON. 

When  the  phlc.giften  combines  ccpioufly  and  inti 
mately  with  earthy  matters  fo  as  to  foim  metals,  it 
probably  fo  difpofes  them,  that  the  primitive  inte 
grant  parts  of  the  new  compound,  that  is,  of  the  me 
tal,  approximate  and  touch  each  other  much  more 
than  the  integrant  parts  of  fimple  earths  can.  This 
is  proved  by  the  great  denfity  or  fpecific  gravity,  and 
ether  general  properties,  of  metals. 

In  fact,  as  we  cannot  conceive  that  a  body  mould 
be  tranfparent,  unlefs  it  have  pores  and  interftices 
through  which  rays  of  light  can  pafs  ;  therefore  the 
more  denfe  a  body  is,  that  'is,  the  fewer  fuch  inter- 
ilices  it  has,  the  lefs  tranfparent  it  will  be  ;  fo  that  the 
denfeft  bodies  ought  to  be  the  moft  opaque  as  in  metals. 
The  difpofition  of  the  pores  of  bodies  contributes  alfo 
much  to  their  greater  or  lefs  tranfpatency  ;  and  bodies, 
the  pores  of  which  are  continued  and  ftraight,  are 
more  tranfparent  than  thole  whofe  pores  are  inter 
rupted,  tranfverfe,  or  oblique  ;  fo  that  a  body  may 
be  much  more  tranfparent  than  another  which  is  lefs 
denfe,  as  we  fee  that  glafs  is  more  tranfparent  than 
charcoal.  But  when  other  circumftances  are  equal, 
the  denfeft  bodies  are  the  moft  opaque.  Therefore  the 
opacity  of  bodies  is  proportionable  to  their  denfity, 
and  to  the  deviation  of  their  pores  from  right  and  pa 
rallel  lines, 

From  the  great  opacity  of  metals,  they  probably 
poifefs  both  thefe  qualities  in  an  eminent  degree.  We 
have  feen,  at  the  beginning  of  this  article,  that  the 
luftre  of  metals,  and  their  property  of  reflecting  light 
much  better  than  any  other  fubftance,  are  necerlkry 
confequences  of  their  opacity.  This  is  alfo  felf-evi- 
dent,  becaufe  the  fewer  rays  any  body  can  tranfmit, 
*Ue  more  it  muft  reflect. 

JLaftlr, 


C     34'     3 

Laftly,  the  ductility  of  metals  proceeds  alfo  from 
their  denfity,  from  ti  e  diipofmon  of  their  pores,  and 
from  the  action  of  latent  heat ,  for  even  the  mcft 
brittle  bodies,  fuch  as  glafs,  fealing-wax,  &c.  become 
ductile  by  heat.  The  foitnefs,  fufibility,  and  volati 
lity,  of  which  all  metals  partake  more  or  lefs,  and 
which  many  •;  f  them  poflcfs  in  a  fuperior  degree,  being 
properties  entirely  contrary  to  thofe  of  the  earthy  prin 
ciple,  probably  proceed  from  the  inflammable  prin 
ciple. 

The  order  in  which  metals  compared  with  each 
other  pofiVfs  moft  eminer.tly  their  principal  properties, 
is  the  fame  as  that  in  which  they  are  here  enumerated, 
beginning  always  with  that  metal  in  which  the  proper 
ty  is  moil  coniiderable. 

1.  Spicifc gravity  or  dcnfty.     Platina,  gold,  mercu 
ry,  lead,  (ilver,  copper,  iron,  and  tin. 

2.  Opacity.     We  cannot  well  compare  metals  with 
each  other  in  this  refpeet,  becaufe  it  is  fo  considerable  in 
all,  that  it  feems  complete.      If,  however,  they  differ 
in  this  refpecl,  the  fame  order  will  ferve  for  opacity  as 
for  denOty. 

3.  Metallic  litflrc  or  Ir'illiancy.     The  fame  obferva- 
tion   which   was  made  concerning  the  laft  mentioned 
property  is  applicable  to  this   alfo.     We  muft,  how 
ever,  obferve,  that  as  by  polifh  bodies  are   rendered 
brighter,  and  that  as  whitenefs   contributes  rBuch  to 
the  reflection  of  light,  the  whiteft  and  hardeft  metals 
therefore  reflect  beft.     Hence  according  to  Mr  Mac- 
quer,  platina  ought  to  be  placed  firft  ;  and  then  iron, 
or  rather  fteel,  filver,  g  Id,  copper,  tin,  lead. 

Hardnefs  of  metals  may  contribute  much  to  the  du 
ration  of  their  polilh  ;  but  certainly  foft  metals,  if  their 
texture  be  equally  compact,  are  no  lefs  capable  ot  re- 
ceivi:  g  a  poliih  than  hard  rmtals.  Some  hard  metal 
lic  allays  have  been  found  to  be  lefs  liable  to  tarnifh 
than  fofter  compounds,  and  have  for  this  reaf^n  alfo 
been  chie3y  ufed  for  fpeculums.  The  property  of  re 
flecting 


[     34*     ] 

hefting  light  feems  chiefly  to  depend  on  the  defends 
of  the  particles  or  on  the  denfity,  on  the  fro  o> -thuds 
of  the  furface,  and  on  the  colcir  being  «io.ft  nru<;ar  to 
the  col.  ur  of  the  light  to  be  reflected.  The  white 
metals,  iilver,  mercury,  tin,  r-fl.ct  light  rm>rt.  -ibim* 
danily  than  others.  Gold,  b?irg  the  denfcft  meta'  rext 
to  platina,  and  perhaps  "becaufe  the  colour  of  f<  1  r 
Imht  has  a  flight!}1  yellowifh  tinge,  dees  alfo  reflect 
light  very  copioufly.  Hence  fpeculums  made  of  leaf- 
gold  have  been  found  to  he  very  powerful.  Iron  or 
ilecl  reflect?  much  lefs»  light  than  any  of  the  abovemen- 
tiuned  metals,  although  Mr  Macquer  has  confidered 
it  as  capable  of  a  greater  reflective  power.  Platina  is 
generally  in  fo  fmall  grains,  that  its  reflexive  power 
cannot  eafily  he  determined.  The  precife  degrees  of 
that  power  which  ought  to  be  affi^ned  to  each  of  the 
abovementioned  metais,  cannot  without  accurate  ex 
periments  be  ascertained.  Perhaps,  howevtr,  their 
reflective  powers  will  be  found  to  be  more  nearly  in  the 
following  order,  than  in  that  abovementioned  from 
M;  Macquer.  Silver,  quickiilver,  tin,  gold,  copper, 
iron,  lead. 

4.  Duft'llfy.     Gold,  filver,  copper,  iron,  tin,  lead. 
The  ductility  of  mercury  and  that  of  platina  are  not  yet 
deteim  ned. 

5.  Hardncfs.    Iron,  platina,  copper,  filver,  gold,  tin, 
and  lead. 

6.  Tenacity.      By  tenacity  we  underftand  the  force 
•with  which  the  integrant  parts  of  metals  rend  their 
feparation.     This  force  appears  to  be  in  a  compound 
ratio  of  their  ductility  and  harcnefs.     The  compara 
tive    tenacity  of  metals  is    meafured  by   the  weight 
which  wires  cfthe  fame  dianjeter,  made  ofthefeveral 
metals,  can  Altai n   without    breaking.     Gold   is  the 
moil  tenacious;  then  iron,  c  pper,  iilver,  tin,  lead. 
The  tenacity  of  mercury  is  unknown  ;  that  of  pla 
tina  is  not  yet  determined,  'but  is  probably  confider- 
able. 

7.  Fufib'ility* 


[     343     ] 

y.  Fufibility.  Mercury,  tin,  lead,  filver,  gold,  cop 
per,  iron,  and  laftly  platiria,  which  cannot  be  fufed  by 
the  grcateft  fire  of  our  furnaces,  but  only  by  the  iolar 
focus,  or  by  a  fire  excited  by  dephlogifticated  air. 

SECT.   II.      Of  Mines  and  Ores  In  general. 

THE  fubftances  found  naturally  combined  with  me- 
tals  in  the  earth,  are,  particularly  fulphur  and  arfenic, 
ibmetimes  feparately,  but  generally  conjointly.  Me- 
tals  combined  with  thefe  fubftances  are  called  metals 
mmeralijed  by  fulphur •,  or  by  arfenic,  or  by  fulphur  and 
arfenic  i  and  thefe  matters  are  called  mineraltfng  fub 
ftances. 

Befides  the  fulphur  and  arfenic  with  which  metals 
are  (Iriclly  combined  in  the  mineral  (late,  they  are  alfa 
pretty  intimately  combined  with  earthy  fubtlances,  of 
different  natures,  and  more  o-r  lefs  divided. 

Thefe  different  matters  united  together  form  maMes 
which  are  compact,  heavy,  brittle,  and  frequently  pof- 
feiied  of  much  metallic  laftre.  Thefe  fubiiances  are 
properly  called  ores,  or  the  matter  of  mines, 

Thefe  ores  are  found  in  earths  and  ftoncs  of  different 
kinds,  as  fands,  flints,  cryftals,  dates,  indurated  clays, 
according  to  the  ground  in  which  they  are  contained. 
But  two  kinds  of  (lones  in  particular  feem  to  accom 
pany  ores ;  and  have  therefore  been  confidered  by  fe- 
veral  mineralogifts  as  matrixes  in  which  metals  are 
formed.  One  of  thefe  (tones  is  a  kind  of  cryftal,  ge 
nerally  white,  milky,  and  femi-opaque,  fcriking  fire 
with  fteel,  and  of  the  clafs  of  verifiable  earths.  It  is 
called  QJJARTZ. 

The  other  ftone  is  lefs  hard,  which  does  not  ftrike 
fire  with  ileel,  and  is  fomctimes  milky  like  quartz  ; 
fometimes  tranfparent  and  of  different  colours ;  con- 
fifting  of  rhornboidal  cryftals,  which  are  compofed  of 
plates  and  faces.  This  (lone  becomes  more  ibft  and 
friable  by  being  expofed  to  fire.  It  is  calledjjter.  Spar 

is 


t     344     ] 

is  more  like  to  gypfeous  ftones  than  to  any  other,  but 
it  differs  from  gypfeous  ftones  in  pofleffing  a  much 
greater  denfity.  Some  fpars  are  fo  heavy,  that  they 
exceed  in  this  refpect  all  other  ftones.  See  SPAR. 

Thefe  earthy  and  ftony  fubftances  form  the  matrix 
cf  the  ore* 

Ores  are  natural  compounds,  containing  metals  al 
layed  with  different  fubftances. 

Excepting  gold,  and  a  very  fmall  quantity  of  each 
of  the  other  metals  found  in  ibme  places  fo  pure  as  to 
pojTefs  all  their  chara&eriftic  properties,  nature  exhi 
bits  to  us  metals  and  femimetals  differently  allayed  not 
only  with  each  other,  but  alfo  with  feveral  heteroge 
neous  fubftances,  which  fo  alter  and  difguife  their  qua 
lities,  that  in  this  ftate  they  cannot  ferve  for  any  of  the 
purpofes  for  which  they  are  proper  when  they  are  fui> 
ficiently  pure. 

Ores  ccnfift,  I.  Of  metallic  fubftances  cahtned ;  or, 
2.  Of  thefe  fubftances  combined  with  other  matters, 
with  which  they  are  faid  to  be  mneralifcd. 

Calcined  metallic  fubftances,  or  caldform  orest  are 
metallic  fubftances  deprived  of  phlogifton,  and  in  the 
ftate  of  a  calx  or  metallic  earth.  Such  are  &\l  ferru 
ginous  ochres,  which  are  calces  of  iron. 

Mineralifed  ores,  are,  I.  Simple,  containing  only  one 
metallic  fubftance ;  or,  2.  Compound,  containing  two 
or  more  metallic  fubftances. 

Of  the  fimple,  and  alfo  of  the  compound  ores,  four 
kinds  may  be  diftinguifhed. 

1.  Ores  confiftin  %  of  metallic  fubftances  mineralifed 
by  fulphur.     Such  is  the  lead-ore  called  galena,  com- 
pofed  of  lead  and  fulphur. 

2.  Ores  confiding  of  metallic  fubftances  mineralifed 
by  arfenic.     Such  la  the  white  pyrites,  containing  iron 
and  arfenic. 

3.  Ores  confining  of  metallic  fubftances  mineralifed 
lyfulphur  and  by  arfenic.     Such  is  the  red  filler-ore,  con 
taining  filver,  arfenic,  and  fulphur. 

4.  Ore* 


[     345     ] 

4.  Ores  confiding  of  metallic  fubftances  mmeralifed 
by  faline  matters.  Such  are  the  native  "jitrish.  Such 
allo  is  probably  the  corneous  fifosr-nre,  which,  accord 
ing  to  Mr  Cronftedt's  opinion,  is  a  luna  cornea,  or  fil- 
ver  combined  with  marine  acid.  Of  this  kind  of  ores, 
or  native  metallic  falts,  is  perhaps  tke ffdatii&fett  of 
borax,  which  from  Mr  Cadet's  experiments,  published, 
in  the  Memoires  of  the  royal  Academy  for  the  year 
176^,  is  conjectured  to  be  coppc-  combined  with  ma 
rine  acid,  and  which  has  been  ikiu  to  bs  found  native. 
To  this  clafs  alfo  may  be  referred  \\\Q  fiver  mineralifcd 
ly  an  alkalme fubftantt,  which  ivfr  Von  Jufti  pretends  to 
have  difcoveied. 

Henckel,  and  after  him  Cramer,  and  the  author  of 
the  Dictionary  of  Chemiftry,  pretend,  that  in  .minera- 
lifed  ores,  beiides  the  abovementioned  metallic  and 
mir.eralifmg  fubftances,  are  alfo  contained  a  metallic 
and  an  unmetallic  earth.  But  Wallerius  affirms,  that 
the  exiftence  of  fuch  earths  cannot  be  fliown,  and  that 
fulphur  is  incapable  of  diflblving  unmetallic  earths,  and 
even  the  calces  of  all  metallic  fubftances,  excepting 
thofe  of  lead,  b;fmuth,  and  nickel. 

Metals  and  metalliferous  crcs  are  found  in  various 
places. 

I.  Under  wafer  ;  in  beds  of  rivers,  lakes,  and  feas, 
.jn.i  chiefly  at  the  flexures  of  thefe :  fuch  are  the  au 
riferous  and  feiruginerusfands,  grains  of  native  gold, 
ochres,  and  fragments  cf  ores  Wiflied  from  mines. 

II.  D'ljji l-vecl  innvahr  :  fuch  are  the  vitriolic  waters 
containing  iron,  copper,  or  /inc. 

III.  Upon  the  fit  "face  of  the  earth.      Such   are    many 
ochres;  metalliferous  ftoues,  fands,  and  clays;    and 
lumps  cf  ores.     Mr  Gmelin  fays,  that  in  the  northern 
parts  of  Afia  ores  are  almcfl  always  found  upon  or 
near  the  furface  of  the  ground. 

IV.  Umlir  tie  furfii'-s  of  tie  earth.     When  the  quar,- 
tity  of  thefe  colkcic;]  in  one  place  is  confiderable,  it  is 

rd  a  mine, 

Subtei 


t  346  ] 

Subterranean  metals  and  ores  are  differently  difpo- 
fed  in  different  places. 

1.  Some  are  infixed  inftones  and  earths ^  forming  no 
dules  or  f pots  diverfely  coloured. 

2.  Some  are  equably  and   uniformly   dlffufed  through 
tie  fubjlance  of  earths  and  fanes,  to  which  they  give  co 
lour,  deniity,  and    other    properties.     Such  are  the 
greateft  part  of  thofe  earths,  (tones,  lands,  clays,  cry- 
ilals,  flints,  gems,  and  fluors,  wliich  are  coloured. 

3.  Some  form  Jlrata  in  mountains.      Such  are  the 
dates  containing  pyrites,  copper-ore,  lead-ore,  filver- 
ore,  or  blend.     Thefe  lie  in  the  fame  direction  as  the 
ftrata  of  (tones   betwixt   which  they  are  placed  ;  but 
they  differ  from  the  ordinary  ftrata  in  this  circum- 
ftance,  that  the  thicknefs  of  different  parts  of  the  fame 
metalliferous  ftratum  is  often  very  various  ;  whereas 
the  thicknefs  of  the  ftony  itrata  is  known  to  be  gene 
rally  very  uniform. 

4.  Fragments  of  ores  are  frequently  found  accumu 
lated  in   certain  fubternmean  cavities,  in   fiifures   of 
mountains,    or  inter pofed  betwixt    the    ftrata  of  the 
earth.     Thefe  are  loofe,  unconnected,  frequently  in 
volved  in  clay,  and  not  accreted   to  the  contiguous 
rocks  or  ftrata  immediately,  nor  by  intervention  of 
fpar  or  of  quartz,  as  the  ores    found    in  veins  are. 
Tin, and  iron  mines  are  frequently  of  the  kind  here  de- 
fcribed. 

5.  Large  entire  mafTes  of  ores  fometimes  found  in 
the  ftony  ftrata  of  mountains.     Thefe  are  improperly 
called  accumulated  veins,  be caufe  their  length,  relative 
ly  to  their  breadth  and  depth,  is  not  conliderablc. 

6.  Some  inftances  are  mentioned  of  entire  mountains 
confifting  of  ore.      Such  is  the  mountain  Taberg  in 
Smoland  ;  and  fuch  are  the  mountains  of  KeruBavara 
and  Luofavara   in  Lapland,  the   former  of  which  is 
1400  perches  long   and  100  perches   broad.     Thefe 
mountains  confiit  of  iron  ere. 

7.  Laftly, 

2 


[     347     ] 

7-  Laftly,  and  chiefly,  metals  and  ores  are  found  in 
oblong  tracts,  forming  malTes  called  veins,  which  lie  in 
the  ftony  ftrata  compcfing  mountains.  See  the  article 

MINE. 

SECT.  III.     Of  tie  Pyrites. 

PYRITE  is  a  mineral  refembling  the  true  ores  of  me* 
tals,  in  the  fubftances  of  which  it  is  compofed,  in  its 
colour  orluftre,  in  its  great  weight,  and,  laftly,  in  the 
parts  of  the  earth  in  which  it  is  found,  fince  it  almoft 
always  accompanies  ores.  It  is,  like  ores,  compofed 
of  metallic  fubftances,  mineralized  by  fulphur  or  by 
arfenic,  or  by  both  thefe  matters,  and  of  an  unmetal- 
lic  earth  intimately  united  with  its  other  principles. 

Notwithstanding  the  conformity  of  pyrites  with  ores 
properly  fo  called,  fome  chemifts  and  metallurgies  di- 
i-tinguifn  the  former  from  the  latter  minerals ;  becaufe 
the  proportion  and  connection  of  the  materials  compo- 
fmg  the  pyrites  differ  much  from  thofe  of  ores.  Thus, 
although  fometimes  pyrites  contains  more  metal  than 
fome  ores,  yet  generally  it  contains  lefs  metal,  and  a 
larger  quantity  of  mineralifing  fubftances,  fulphur  and 
arfenic,  and  particularly  of  unmetallic  earth.  The' 
connection  of  thefe  matters  is  alfo  much  ftronger  in 
pyrites  than  in  ores,  and  they  are  accordingly  much 
harder  ;  fo  that  almoft  every  pyrites  can  ftrike  fparks 
from  ft  eel. 

From  the  above  property  of  ftriking  fparks  from 
fteel,  they  have  been  called  pyrites ;  which  is  a  Greek 
word  fignifying^r^cw^.  Pyrites  was  formerly  ufed 
for  fire-arms,  as  we  now  ufe  flints  :  hence  it  was  called 
carallne-Jlone.  It  i?  ftill  named  by  fome,  marcafite.  Per 
haps  no  other  kind  of  natural  body  has  received  fc) 
many  names.  Perfons  curious  to  know  the  other  names 
lefs  ufed  than  thofe  we  have  mentioned,  may  find  them 
in  Henkle's  Pyri-v/ogia.  We  th'nk,  with  that  cele 
brated  chemift,  that  the  fubject  has  been  perplexed  by 
F  f  this 


I    S4*     3 

this  multiplicity  of  r,ames  ;  for  before  his  great  and 
excellent  work,  the  notions  conctrsing  pyrites  were 
very  confufed  and  inaccurate. 

Pyrite  differs  alfo  from  ores  by  its  forms  and  pofi- 
tions  in  the  earth.  Although  pyritous  metals  generally 
precede,  accompany,  and  follow  veins  of  ores  ;  they  do 
not,  properly  i peaking,  themfelves  form  the  oblong 
and  continued  maffes  called  veins,  as  ores  do  ;  but  they 
form  mafles  fometimes  greater  and  fometimes  fmaller, 
but  always  diftincl  from  each  other.  Large  quanti 
ties  of  them  are  often  found  unaccompanied  by  ore?. 
They  are  formed  in  clays,  chalk,  marles,  marbles,  pla- 
fters,  alabafters,  Hates,  fpars,  quartz,  granites,  cryihils, 
in  a  word,  in  all  earths  and  ftones.  Many  of  them  are 
alfo  found  in  pit-coals  and  other  bituminous  matters. 

Pyrites  is  alfo  diftinguifhahle  from  ores  by  its  luftre 
and  figure;  which  is  almoft  always  regular  and  uni 
form,  externally  or  internally,  or  both.  Some  ores 
indeed,  like  thcfe  of  lead,  many  ores  of  filver,  and  fome 
others,  have  regular  forms,  and  are  in  feme  manner 
cryftallized;  but  this  regularity  of  form  is  not  fo  uni- 
verfal  and  fo  confplcucus  in  ores  as  in  pyrites.  The 
luftre  of  pyrites  feems  to  be  caufed  by  its  hardnefs, 
and  the  regularity  of  its  form  by  the  quantity  of  mi- 
neralifmg  fubftsnces  v  hich  it  contains. 

By  all  thefe  marks  we  may  eafily,  and  without  ana- 
lyfis,  diftinguifh  pyrites  from  true  ores.  When  we  fee 
a  mineral  that  is  heavy,  poifelTed  of  metallic  luftre,  and 
of  any  regular  form,  the  mafs  of  which  appears  evi 
dently  to  be  entire,  that  is,  not  to  have  been  a  frag 
ment  of  another  mafs,  and  which  is  fo  hard  as  to  be 
capable  of  fti  iking  fparks  from  fteel,  we  may  be  a  (lu 
red  that  fuch  a  mineral  is  a  pyrites,  and  not  an  ore. 

The  claf^  <  f  pyrites  is  very  numerous,  various,  and 
extenfive.  They  differ  one  from  another  in  the  nature 
and  proportions  of  their  component  parts,  in  their 
forms,  and  in  their  colours.  The  forms  of  thefe  mi- 
fcerals  are  exceedingly  various.  No  fblid,  regular  or 

irregular, 


[     349     ] 

irregular,  can  eafily  be  conceived,  that  is  not  p.erfeclly 
imitated  by  fonie  kind  of  pyrites.  They  are  fplieri- 
cal,  oval,  cylindrical,  pyramidal,  prifmatical,  cubic  ^ 
they  are  folids  with  5,  6,  7,  8,  9,  10,  &c.  fides.  The 
furface  of  fome  is  angular,  and  coniifts  of  many  bafes 
of  fmall  pyramids  ;  while  their  fubftance  is  compofed 
of  thefe  pyramids,  the  points  of  which  all  unite  in  the 
centre  of  the  mafs. 

Pyritous  minerals  differ  alfo  in  their  component  fub- 
ftances.  Some  of  them  are  called  fulphureous,  martial, 
cupreous,  arfcnlcal,  as  one  or  other  of  thefe  fubftances 
predominate.  We  mud  obferve  with  Henckel,  whofe 
authority  is  very  great  in  this  fubject,  that  in  general 
all  pyrites  are  martial ;  as  ferruginous  earth  is  the  ef- 
fential  and  fundamental  part  of  every  pyrites.  Thi* 
earth  is  united  with  an  unmetallic  earth,  with  fulphiu* 
or  arfenic,  or  with  both  thefe  matters  ;  in  which  cafe, 
the  fulphur  always  predominates  over  the  arfenic,  as 
Henckel  obferves.  He  confiders  thefe  as  the  only  ef- 
fer.tial  principles  of  pyrites  ;  and  believes  that  all  the 
other  matters,  metallic  or  unmetallic,  which  are  found 
in  it,  are  only  accidental ;  amongft  which  he  even  in 
cludes  copper,  although  fo  much  of  it  exills  in  fome 
kinds  of  pyrites,  that  thefe  are  treated  as  ores  of  cop- 
per,  and  fometimes  contain  even  5olb.  of  copper  each 
quintal.  Many  other  metals,  even  gold  arid  lilver,  are 
fometimes  combined  in  pyrites ;  but  thefe  are  lei's  fre 
quent,  and  the  precious  metals  always  in  very  fmall 
quantities  ;  they  are  therefore  juftly  to  be  considered  as 
accidental  to  pyrites  The  different  fubftances  compo- 
fuig  pyiites  feniibly  ai'lx'tf  its  colours.  Henckel  di- 
Ainguiflies  them  in  general  into  three  colours,  white, 
yellowiil],  or  a  pale  yellow,  and  yellow.  He  informs 
us,  that  thefe  three  colours  are  often  fo  blended  one 
with  another,  that  they  cannot  .be  eafily  diftinguimed 
unlefs  when  compared  together. 

The  white  pyntes  contain  moft  arfenic,  and  are  il- 
»uil,j*r  to  cobalt  and  other  minerals  abounding  in  arfe- 

F   f    2  DIC» 


C     25°     3 

'•T.ic.  The  Germans  call  them  tntjffit&te,  or  mifclii.  Iron 
and  arfenic  form  the  greateft  part  of  this  pyrites.  As 
-,irfenic  has  the  property  of  whitening  copper;  force 
pyntous  minerals  almott  white,  like  that  of  Chemnitz 
in  Mifnia,  are  found  to  contain  40  pounds  of  copper 
per  quintal,  and  which  are  fo  much  whitened  by  the 
-.srfenic,  that  they  are  very  like  white  pyrites.  But 
H -nickel  obferves,  that  thefe  pyritous  matters  are  very 
rare,  and  are  never  fo  white  as  the  true  white  pyrites, 
which  is  only  ferruginous  and  arfenical. 
•  Yellowifli  pyrites  is  chiefly  compofed  of  fulphur  and 
iron.  Very  little  copper  and  arfenic  are  mixed  with 
any  pyrites  of  this  colour,  and  inoft  of  them  contain 
none  of  thefe  two  metallic  fubftances.  This  i.s  the  moil 
common  kind  of  pyrites  :  it  is  to  be  found  almoft  every 
where.  Its  forms  are  chiefly  round,  fpherical,  oval, 
flattened,  cylindrical ;  and  it  is  compofed  internally  of 
needles  or  radii,  which  unite  in  the  centre,  or  in  the 
axis  of  the  foUd. 

Yellow  pyrites  receives  its  colour  from  the  copper 
and  fulphur  which  enter  into  its  compofition.  Its  co 
lour,  however,  is  inclined  to  a  green  ;  but  is  fufnciently 
yellow  to  diftinguifh  it  from  the  other  two  kinds  of 
pyrites,  particularly  when  they  are  compared  together. 
To  make  this  comparifon  well,  the  pyrites  muft  be 
broken,  and  the  internal  furfaces  mufl  be  placed  near 
each  other.  The  reafon  of  this  precaution  is,  that  die 
colour  of  minerals  is  altered  by  expofure  to  the  air.  ; 

Perfons  accuftomed  to  thofe  minerals  can  eafily  di- 
ftin'g-uifti  them.  The  chief  difficulty  is,  to  dittingmili 
white  pyrites  from  cobalt  and  other  minerals ;  which 
alfo  contain  fome  copper  and  much  arfenic. 

Hence  then  v\e  fee,  that  arfenic  is  the  caufe  of  white1- 
fiefs  in  pyrites,  tind  is  obtained  in  every  pyrites  of 
that  colour ;  that  copper  is  the  principal  caufe  of  the 
yellow  colour  of  pyrites  ;  and  that  every  pyrites  which 
is  evidently  yellow  contains  copper ;  that  fulphur  and 
iron  produce  a  p.ile-yellpw  colour,  which  is  alfo  pto:- 

duccd 


[     35'     3 

duced  by  copper  and  arfenic  ;  hence  fome  difficult;  JT 
may  arife  in  diitingutihing  pyiites  by  its  colours.  We 
may  alfo  obferve,  that  fulphur  and  arfenic,  without  any 
other  fubitance,  form  a  yellow  compound,  as  we  fee 
from  the  example  of  orpiment  or  yellow  arfenic.  Thus, 
although  the  colours  of  the  pyrites  enable  us  to  diilin- 
guifh  its  different  kinds,  and  to  know  their  nature  at 
firft  fight,  particularly  when  we  have  been  accuftomed 
to  obferve  them  ;  yet  we  cannot  be  entirely  certain 
concerning  the  true  nature  of  thefe  minerals,  and  even 
of  all  minerals  in  general  ;  that  is  to  know  precifely 
the  kinds  and  proportions  of  the;r  component  Jubilan 
ces,  but  by  chemical  analyiis  and  decomposition. 

Beiides  the  abovementioned  matters  which  com- 
pofe,  pyrites,  it  alfo  contains  a  considerable  quantity  -oi 
unmetallic  earth  ;  that  is,  an  earth  which  cannot  by 
any  procefs  be  reduced  to  metal.  Henckel,  Cramer, 
and  all  thole  who  have  examined  this  matter,  men 
tion  this  earth,  and  prove  its  exigence. 

We 'ought  to  obferve,  that  this  earth  is  combined, 
with  the  other  principles  of  the  pyrites,  and  not  mere 
ly  interpofcd  betwixt  its  parts.  It  muft  therefore  be 
diRinguifhed  from  other  earthy  and  ftony.  matters  mix 
ed  accidentally  with  pyrites,  and  which  do  not  make 
a  part  of  the  pyrites,  in-ice  they  may  be  feparated  by 
mechanical  means,  and  without  decompoilng  that  mi 
neral  :  but  the  earth  of  which  we  now  treat  is  inti 
mately  united  with  the  other  confUtuent  parts  of  the, 
pyrites,  is  even  a  conitituent  part  of  pyrites,  and  ef- 
fential  to  the  existence  of  this  mineral,  and  cannot  be 
feparated  but  by  a  total  decompofition  of  it,. 

According    to  Henckel,    this  unmetallic    earth  a-.. 
bounds   much  in  the  white  pyrites,    fince  he   found: 
from  the  analyfes  which  he  made,  that  the  iron,  which- 
is  the  only  metal  exitting  in  thefe  pyrites,  is  only  about 
sJ-^th  part  of  the  fixed  fubftance  that,  remains,  after  the 
arfenic  has  been  expelled  by  torrefaclion  or.  fublima-, 
t^p-n. 

I  f  3 


A  much  Lirger  quantity  of  iron  is  in  the  pale  yel 
low  pyrites,  according  to  Henckel.  The  proportion 
of  iron  is  generally  about  12  pounds  to  a  quintal 
of  pyrites,  and  fometimes  50  or  60  pounds  :  this  is 
therefore  called  martial  pyrites.  It  contains  about 
one-fourth  of  its  weight  of  fulphur,  and  the  reft  is 
unmet allic  earth. 

The  quantity  of  unmeullic  earth  contained  in  the 
yellow  or  cupreous  pyrites,  which  are  alfo  martial, 
fmce,  as  we  have  obferved,  iron  is  an  efTential  part  of 
every  pyrites,  has  not  yet  been  determined.  They 
probably  contain  fome  of  that  earth,  though  perhaps 
Icfs  of  it  than  the  others. 

The  nature  of  this  unmetallic  earth  of  pyrites  has 
rot  been  well  examine^.  Henckel  thinks  that  it  is  an 
earth  difpofed  already  by  nature  to  metallifation,  but 
not  fufficiently  elaborated  to  be  confidered  as  a  metal- 
}:c  earth.  This  opinion  is  not  improbable;  but  as 
alum  may  be  obtained  from  many  pyrites,  may  we  not 
fufpecl  that  this  unmetallic  earth  is  of  the  nature  of 
the  bafis  of  alum  of  argillaceous  earth  ?  Perhaps  alfo 
this  earth  is  different  in  different  kinds  of  pyrites. 
The  fubjecl  deferves  to  be  well  examined, 

Although  pyrites  are  not  fo  valuable  as  true  ores, 
hecaufe  in  general  it  contains  lefs  metal,  and  but  ex- 
-c  :edingly  little  of  the  precious -metals  ;  and  becaufe  its 
metallic  contents  are  fo  difficult  to  be  extracted,  that 
excepting  cupreous  pyrites,  which  is  called /jr/Voi/j  cop* 
per  ore,  it  is  not  worked  for  the  fake  of  the  contain 
ed  metal  ;  yet  it  is  applied  to  other  purpofes,  and  fur- 
ruilies  us  with  many  ufeful  fubftances ;  for  from  it  we 
obtain  all  our  green  and  blue  vitriols,  much  fulphur, 
orfemc,  and  or  p' merit.  See  the  principal  proceffef  by 
which  thefe  fubjlatices  are  extracted  from  pyrites,  under  the 
fc^lion  SMELTING  of  ORES. 

As  all  pyrites  contain  iron,  and  moft  of  them  con-: 
tain  alfo  fulphur  ;  as  the  pyrites  moft  frequently  found 
contains  only  thefe  two  fubilances  with  the  unme* 

talUc 


[     353     1 

tallic  earth ;  and  as  iron  and  fulphur  have  a  fmcnilar 
action  upon  each  other  when  they  are  well  mixed  to- 
gether  and  moifteifed  ;  hence  many  kinds  of  pyrites, 
particularly  thefe  ..which  contain  only  the  principles 
now  mentioned,  fuftain  a  fmgular  alteration,  and  even 
a  total  decompofition,  when  expofed  during  a  certain 
time  to  the  combined  action  of  air  and  water.  The 
moiihire  gradually  penetrates  them,  divides  and  atte 
nuates  their  parts  ;  the  acid  of  ihe  fulphur  particularly 
attacks  the  martial  earth,  and  alfo  the  unmetallic  earth; 
its  inflammable  principle  is  feparated  irom  it,  and  is 
diiiipated.  While  thefe  al  eratiens  happen,  the  py 
rites  changes  its  nature.  The  acid  of  the  fulphur 
which  is  decompofed,  forms  with  the  fixed  principles 
of  the  pyrites,  vitriolic,  aluminous,  and  felenitic  falts  J 
fo  that  a  pyrites,  which  was  once  a  ihining,  cornpa&j 
very  hard  mineral,  becomes  in  a  certain  time  a;  grey  iffy 
faline,  powdery  mafs,  the  taite  of  which  is  faline,  au* 
ftere,  and  ftyptic. 

Laftly,  if  this  mafs  he  lixiviated  with  water,  cryftals 
of  vitriol,  nn.l  fomnimes  of  alum,  according  to  the  na 
ture  of  the  pyrites  emploj  ed,  may  be  obtained  by  eva 
poration  and  cryfta  Ir/ation. 

Th's  alteration  and  fpontaneous  decom:*  fit  ion  of 
pyrites,  is  ca1led  efflvrefience  arid  •uitrio'izafion  ;  becaufe 
the  pyrites  becomes  covered  with  a  faline  powder,  and 
becaufe  vitriol  is  always  formed.  This  vitriolization  is 
raore  or  lefs  quickly  accompliihed  :in  pyrites  according' 
to  its  rature.  It  is  a  kind  of  fermentation  excited  by\ 
moifture  amr»ngft  the  condiment  j  arts  cf  thefe  mine-1 
xals ;  and  it  is  fo  violent  in  thofe  which  are  moil  ciif- 
pofed  to  it,  that  ic,  in  the  pale  yellow  pyrites,  v.hich 
contain  chiefly  fulphur  and  iron,  that  when  the  q:.>a§-. 
tity  of  thefe  is  confiderable,  not  only  a  fnlphu=  t(  u.-  va 
pour  and  heat  may  be  perceived  but  alfo  the  v.'.ole 
kindles  and  burns  intenfely.  The  fame  phen'omei..i  are 
obfervablr.-,  anH  the  fame  refults  are  formed,  by  mix 
ing  well  together,  and  moiftening  a  large  quantity  of 

filings 


C     3H     I 

hlings  of  iron  and  powdered  fulphur 

nient  Lemeri  has  made  to  explain  the  caufes  of  fub- 

terranean  tires  and  volcanoes. 

We  cannot  doubt,  that,  as  the  earth  contains  very- 
large  maffes  of  pyrites  of  this  kind,  they  muft  undergo 
the  fame  changes  when  air  and  moitiure  penetrate  the 
cavities  containing  them  ;  and  the  betl  natural  philofo- 
phers  agree,  that  very  probably  this  iarpriiing  decom- 
pofiti'-n  of  pyrites  is  the  cauie  ot  fubterr  mean  fires,  of 
vcl-.anoes,  a:  id  of  mineral  waters,  vitriolic,  aluminous, 
fiilphtireou",  hot  and  cold. 

No  other  pyrites  is  fubjecl:  to  this  fpontaneous  de- 
corapofitiun  when  exp  fed  t<>  humid  air,  but  that,  which 
is  both  martial  and  tulphureous  ;  that  is,  the  pale- 
yellow  pyrites.  The  arfenizal  pyrites,  or  that  which 
contains  tittle  or  no  fulphur,  is  not  changed  by  expo- 
fure  to  air.  This  latter  kind  is  harder,  heavier,  and 
more  compact  than  the  former.  The  pyrites  which  is 
angular  and  regularly  ftiaped,  is  chiefly  of  this  kind. 
Mr  Wallerius  in  his  Mineralogy,  propofes  to  Jifiin- 
guifh'this  kind  of  pyrites  by  the  name  of  warca/ita. 
"When  cut,  it  may  be  poliilied  fo  well  as  to  give  a  lull  re 
almoft  equal  to  that  of  diamonds,  but  without  refrac 
ting  or  <vx>rnpofmg  the  light ;  for  it  is  perfectly  opaque. 
It  has  been  employedTome  years  p.ift  in  the  manufac 
ture  of  toys,  as  of  buckles,  necklaces,  £c.  and  is  call 
ed  in  commerce  marcafite. 

We  cannot,  however,  concur  with  Mr  Macqucr 
(from  whom  the  above  is  taken),  .in  thinking  that 
there  is  fnfficient  reafon  for  confidering  the  minerals 
called  pyrites,  as  a  didinc!  clafs  of  fubftanccs  from  ores. 
They  have  indeed  no  mark  by  which  they  can  certain 
ly  and  conftantly  be  diftinguifhed  from  thefe.  The 
hardnefs  or  property  of  ftriking  ignited  fparks  from 
fteel  is  not  common  to  all  the  fubftances  generally  call 
ed  fyrites  ;  for  we  find  fome  of  thefe  enumerated  by 
mineralogifts  which  have  not  that  property.  Wallerius 
even  mentions  3  pyrites  which  contains  no  iron,  althov 


[     355     3 

that  metal  is' thought  by  K  nickel  to  be  eiTential  to  py 
rites.  The  diilinction  of  pyrites  fr  rn  ores  has  been 
chiefly  introduced  by  miners  ;  becaufe  the  great  eft  part 
of  the  former  minerals  contain  fo, little  metal,  and  fa 
much  of  the  miner  A!  i  (ing  fubftances,  fulphur  or  arfe- 
nic,  that  they  are  feldom  imelted.  Nevertheless,  foms 
kinds  of  pyrites  are  found  which  contain  fo  much  cop 
per,  that  they  are  fmelted  with  great  pr<  .fit,  Accord 
ingly,  fo-me  later  mineralogifts  confider  the  cupreous 
yellow  pyrites  as  an  ore  of  copper,  the  pale-yellow 
martial  pyrites  as  an  ore  of  iron  \  and  the  white  arfe- 
meal  pyrites  as  an  ore  of  nrfenic.  See  Ores  of  Copper^ 
Iron,  and  of  4rfenict  below. 

SECT.  IV.     Effaying  of  Ores  in  general. 

ESSAYS  are  chemical  operations  made  in  fmall,  to 
determine  the  quantity  of  metal  or  other  matter  which 
is  contained  in  minerals ;  or  to  difcover  the  value  or 
purity  of  any  mafs  of  gold  or  filver.  The  former  kind 
is  the  fubjed  of  the  prefent  fe&ion  ;  the  latter  is  treat 
ed  under  the  word  ESSAYS,  in  the  order  of  the  alpha 
bet. 

Before  eflays  of  ores  can  be  well  made,  a  prelimi 
nary  knowledge  of  the  nature  of  the  feveral  metallic 
minerals  ought  to  be  attained.  Each  metal  has  its 
proper  and  improper  ores,  which  have  peculiar  cha 
racters  and  appearances  :  hence  perfons  accuftomed  19 
fee  them,  know  pretty  nearly  by  the  appearance, 
weight,  and  other  obvious  qualities,  what  metal  is  con 
tained  in  a  mineral.  A  good  eflaycr  ought  to  be  very- 
intelligent  in  this  matter,  that  he  may  at  once  know 
what  the  proper  operations  are  which  are  requifite  to 
the  effay  of  any  given  mineral. 

As  metals  are  very  unequally  diftributed  in  their 
ores,  we  (hould  be  apt  to  make  falfe  and  deceitful  ef- 
fays,  if  we  did  not  ufe  all  poffible  precautions  that  the 
proportionable  quar.t'ty  of  metal  produced  by  an  eflay 

{hall 


C     3JG     1 

ft  all  be  nearly  the  medium  contained  in  the  whole 
ore.  This  is  effected  by  taking  pieces  of  the  mi 
neral  from  the  feveral  veins  of  the  mine  if  there  be 
feveral,  or  from  diirerent  place-;  of  the  fame  vein. 
All  thefe  minerals  are  to  be  ihaken  t-ge  her  with 
their  matrixes.  The  whole  is  to  be  well  mixed  toge 
ther,  and  a  convenient  quantify  of  this  mixture  is  to 
be  taken  for  the  eilay.  This  is  called  the  lotting  of  the 
ore. 

As  eflays,  particularly  the  fir[t,  are  generally  made 
in  fin  all,  eiTayers  have  very  fmali  weights  corresponding 
to  the  v/e  glits  ufed  in  the  great;  that  is,  to  the  quin 
tal  or  hundred  pounds  weight,  to  pounds,  ounces, 
drams,  Sec.  The  erTay  quintal  and  its  fubdivifions 
vary  according  to  the  difference  of  weights  in  diffe 
rent  countries;  and  this  occafions  feme  confufion 
wlitn  thefe  weights  are  to  be  adjufted  to  each  other. 
Tables  of  thefe  weights  are  found  in  treatifes  of  e& 
faying  ;  and  particularly  in  that  written  by  Schlut- 
ter,  and  translated  and  rendered  more  complete  by 
Hellot,  which  contains  all  the  details  neceifary  for  ths 
fubjecl. 

The  cuftom  is  to  take,  for  the  eflfay  quintal,  a  real 
weight  of  a  gros,  or  a  dram,  which  in  France  is  equal 
to  72  grains;  but  as  the  whole  dram  reprefents  100 
pounds,  each  grain  reprefents  a  pound  and  a  fraction 
of  a  pound  ;  and  hence  feme  difficulty  and  a  confufion 
arife  in  making  the  fubdivifions.  A  better  method  is 
that  of  Mr  Hellot,  which  is  to  make  the  ficTitious  or 
efiay  quintal  equal  to  100  real  grains,  and  then  each 
grain  reprefents  a  real  pound.  This  effay  quintal,  is 
Sufficiently  exact  for  ores  of  lead,  t*n,  copper,  iron, 
antimony,  bifmuth,  and  mercury.  But  for  ores  of  iil- 
ver  and  gold,  another  representation  is  convenient :  for 
thefe  metals,  as  Mr  Hellot  fays,  are  generally  in  fo 
fmall  quantity,  that  the  button  or  fmall  piece  of  meul 
obtained  in  the  eflay  could  not  be  accurately  weighed 
ii"  JDQ  real  grains  were  made  to  reprefent  a  quintal ; 

anc| 


C     357     ] 

and  the  difficulty  of  feparnting  the  gold- from  fo  finall 
a  quantity  would  be  ftill  greater.  Ti'jeic  mo^Kies  have 
induced  Mr  Hellot  to  ufe  for  thefe  or  us  a  fictitious 
quintal  16  times  bigger  ;  that  is,  equal  to  1600  real 
grains,  which  repreient  1600  ounces  ;  thnt  ic,  loolb. 
or  quintal.  The  ounce  being  reprefemed  by  a.  grain, 
its  feveral  fubdivifions  muft  be  reprefented  by  fractions 
of  a  grain.  Thus  12  grains  of  the  -fictitious  quintal 
correfpond  with  ?\  of  a  real  grain  (*)  ;  and  this  lat 
ter  quantity  may  be  accurately  weighed  in  eilay  balan 
ces  :  which  when  well  made  are  fenfible  to  a  much  left 
weight.  See  (EJky)~Q*\,k*<St. 

When  a  quintal  of  aa  ore  to  be  efluyed  has  been 
weighed,  and  lotted,  as  we  defcribed  above,  it  is  to 
be  roafted  in  a  left  under  a  muffle.  It  is  to  be  wafned, 
if  necelfary  ;  and,  in  fhort,  the  fame  operations  are  to 
be  made  in  fmall  which  are  ufually  done  in  great.  Ad 
ditions  alfo  are  to  be  made,  and  in  proper  proportions, 
according  to  the  peculiar  nature  of  the  ore.  The  fluxes 
generally  mixed  with  the  e flays  in  ore  are  three,  four, 
or  five  parts  of  black  flux  ;  one,  two,  or  three  parts  of 
calcined  borax  ;  and  one  half  of  that  quantity  of  de 
crepitated  common  fait.  The  more  refractory  the  ore 
is,  the  more  neceifary  is  the  addition  of  thefe  fluxes: 
then  the  whole  mixture  is  to  be  fufed  either  in  a  forge 
or  in  a  melting  or  elfay  furnace. 

To  make  eifays  well,  all  poflible  attention  and  ac 
curacy  are  to  be  employed.  This  object  cannot  be  too 
much  attended  to  ;  for  the  leaft  inaccuracy  in  weigh 
ing,  or  lofs  of  the  fmalleft  quantity  of  matter,  might 
caufe  errors,  fo  much  greater  as  the  difproportion  be 
twixt  the  weights  employed  and  thofe  reprefented  is 
greater.  The  moil  minute  accuracy  therefore  is  n ••?- 
ceifary  in  thefe  operations.  For  inlLmce,  the  eflay- 

*  The  pounds,  of  which  100  are  here  fuppofed  to  make  a 
quintal,  aie  called  Paris  pounds,  one  of  which  contains  1269 
Troy  grains, 

balances 


C    353    ] 

balances  ought  to  be  fmall,  and  exceedingly  julh  The 
cie  ought  net  to  be  weighed  till  it  has  been  reduced 
to  grofs  powder  fit  for  roaiMng  ;  becaufe  fome  of  it  is 
always  loft  in  this  pulverization.  When  the  ore  is 
roafted,  it  ought  to  be  coveied  with  an  inverted  teft ; 
becaufe  moil  ores  are  apt  to  crackle  and  difperfe  when 
firft  heated.  To  make  the  fufion  good  and  complete, 
the  preciie  degree  of  fire  which  is  requillte  ought  to 
be  employed ;  when  it  is  finiihed,  the  crucible  ought 
to  be  tfruck  two  or  three  times  with  lome  inihument, 
to  facilitate  the  difengagement  of  the  parts  of  the  regu- 
lus  from  the  fcoria,  and  to  occafion  their  defcent  and 
union  into  one  button  of  metal.  The  crucible  ought 
not  to  be  broken,  nor  its  contents  examined,  till  it  is 
perfectly  cold. 

Upon  breaking  the  crucible,  we  may  know  that  the 
fufion  has  been  good,  if  the  fcoria  be  neat,  compact, 
and  equal ;  if  it  has  not  overflowed  or  penetrated  the 
crucible  ;  if  it  contain  no  metallic  grains  ;  and  if  its 
furface  be  fmooth,  and  hollowed  in  the  middle.  The 
regulus  or  button  ought  to  be  well  collected,  without 
holes  or  bubbles,  and  to  have  a  neat  convex  furface ;  it 
is  then  to  be  feparated  from  the  fcoria,  well  fcraped 
and  cleaned  ;  and,  laitly,  is  to  be  weighed.  If  the  ope 
ration  has  been  well  made,  its  weight  fhows  the  quan 
tity  of  metal  which  every  real  quintal  of  ore  w*ll  yield 
in  the  great.  If  the  perfect  fuccefs  of  this  effay  be  in 
any  reJpect  doubtful,  it  ought  to  be  repeated  ;  but  the 
beft  method  at  all  times  is,  to  make  feveral  eifays  of  the 
fame  ore.  Some  jinall  differences  are  always  found, 
however  well  the  effays  may  have  been  made.  By  ta 
king  the  medium  of  the  results  of  the  feveral  opera 
tions,  we  may  approach  as  nearly  as  pcilible  the  true 
product  oi  the  ore. 

Lyftly,  as  mines  are  not  worked,  nor  founderies 

eftablifned  (which  cannctbe  done  without  ccnfiderable 

expence),  till  the  ore  has  been  eifayed,   10  or  12  real 

pounds  of  the  ore  ought  to  be  previouily  eiTayed  :  and 

4  elTayer* 


[     359    ] 

eflayers  ought  to  be  furnifhed  with  neceflary  furnaces 
and  inftrumeats  for  thefe  larger  eflays. 

In  Part  II.  to  the  feveral  articles  of  the  ores  of  me 
tals,  we  (hall  add  the  mod  approved  method  of  eiTay- 
ing  thefe  ores.  We  fliall  here  only  further  obferve  in  ge 
neral,  that  the  methods  commonly  practifed  for  eflay- 
ing  ores  of  imperfect  metals,  and  femimetials  efpeci.illy, 
are  infufficicnt  to  procure  the  whole  quantity  of  metal 
contained  in  ores,  or  even  fo  much  as  is  obtained  in  the 
imelting  of  large  quantities  of  ores  ;  and  that  there 
fore  the  refult  of  eflays  is  not  to  be  coufidered  as  the 
precife  quantity  contained  in  an  ore,  but  generally 
only  as  an  inaccurate  approximation  to  that  quan 
tity.  M.  Gellert  afcribes  one  caufe  of  the  want  of 
fuccefs  of  thefe  operations  to  the  alkaline  falls  em 
ployed  as  fluxes  to  the  ores,  by  which  moil  metal 
lic  calces  are  partially  foluble,  but  more  efpecially  fo 
when  any  of  the  fulphur  of  the  ore  remains  ;  which, 
by  uniting  with  thefe  falls,  forms  a  hepar  of  fulphur 
which  is  the  moft  powerful  of  all  folvents.  He  propo- 
fes  therefore  to  omit  the  black  flux,  and  other  alkaline 
ihlts,  and  to  add  nothing  to  the  ore  bil£  powder  of 
charcoal  and  fome  fufible  gbifs.  This  method,  h- 
fays,  he  learned  from  Mr  Cramer,  and  has  himfelf 
ufed  with  much  fuccefs  in  the  eflays  of  iron  and  cop 
per  ;  but  finding  that  other  imperfect  metallic  fubftan- 
ces  could  not  fuftaUi  the  heat  necelfary  to  effect  the 
fufion  and  vitrification  of  the  unmetallic  parts  of  the 
ore  without  being  partly  diflipatecl,  he  found  it  ne- 
ceffary  to  add  in  the  eflays  of  theie  latter  metallic  mat 
ters  fome  borax,  by  which  the  fufion  might  be  com 
pleted  wi chiefs  heat.  As  we  confider  this  as  a  confl- 
derable  improvement  in  the  art  cf  eilaying  ores,  we 
(hall,  to  the  articles  of  the  feveral  ores,  add  not  only 
the  procefies  commonly  prefcribcd,  but  alfo  thofe  of 
Mr  Gellert,  according  to  the  method  here  mentioned. 

G  g  PART 


E    S&>    3 
PART     II. 

Containing 

A  SUMMARY  DESCRIPTION  OF  THE  PRIN 
CIPAL  ORES  OF  .EACH  METAL, 

AND 

The  Methods  of  Effacing  them. 


SECTION     I. 
Ores   of  Gold 

§  i.  X  RO3ERLY  fpeaking,  no  ores  of  gold  exift: 
for  as  this  metal  cannot  be  allayed  with  arfenic, 
nor  with  fulphur,  it  is  never  found  directly  minera- 
lifed  by  thefe  fuj>ftances,  as  the  other  metals  are.  In 
the  fecond  place,  if  it  be  mineralifed  indirediy  by 
the  union  it  contracts  with  other  metals  naturally 
<v>»-»ibined  with  fulphur  and  arfenic,  fo  i'mall  a 
quantity  of  it  only  is  found  in  thefe  ores,  that 
they  fcarcely  even  deferve  the  name  of  improper  ores  of 
gold. 

Hence  gold  is  found  either  in  its  natural  Rate,  of 
a  certain  degree  of  purity,  porTdled  of  all  its  proper 
ties  ;  or  engaged  with  fome  other  metals  in  certain 
minerals. 

The  gold  which  is  found  alone  is  called  native  or 
virgin  gold.  This  is  generally  incrufted,  and  fixed  in 
different  kinds' of  ftones,  principally  in  flints  and  quartz. 
Mr  Cramer  fays,  that  ihe  yellow  'brilliant  fpots  of  the 
blue  ftones  called  lapis  lazuli,  are  native  gold  ;  but 
thefe  are  very  fmall. 

TjolS  is  alfo  found  in  fat  and  muddy  earths  ;  and 
.Mr  Cramer  affirms,  that  fcarcely  any  fand  can  be 

found 


found  which  does  not  contain  gold ;  but  he  ac 
knowledges,  at  the  fame  time,  that  the  quantity  is  too 
imall  to  compenfate  for  the  expence  of  obtaining  it. 

Laftly,  the  large  ft  quantity  of  native  gold  is  to  be 
found  in  the  fands  of  fome  rivers.  It  is  chiefly  collected 
in  hollows  at  the  bottom  of  thefe  rivers,  and  at  their 
feveral  bendings.  The  gold  is  collected  in  thefe  places 
by  a  natural  operation,  fimilar  to  that  of  wafliingof  ores. 

A  confiderable  quantity  of  gold  is  in  the  fands  of 
feveral  rivers  in  France :  fo  that  perfons  who  collect 
it  find  enough  to  compenfate  their  trouble.  Mr 
Reaumur,  in  a  memoir  that  he  gave  in  the  year  1718 
concerning  the  rivers  of  France  which  contain  gold, 
enumerates  ten  of  them:  namely,,  the  Rhine,  the 
Rhone,  the  Doux,  the  Ceze,  and  the  Garden  ;  the 
Arreige  ;  the  Garonne ;  two  dreams  which  flow  into 
tl;e  Arreige,  called  Fernet  ancf  Benagues ;  laftly, 
the  Salat,  the  fource  of  which  is  in  the  Pyrenean 
mountains. 

The  Ceze  is  the  river  which  furrrifhes  the  largeft 
quantity  of  gold  at  certain  times.  Mr  Reaumur  ob- 
ferves,  that  its  particles  are  larger  than  thofe  of  the 
Rhine  and  of  the  Rhone ;  and  fays,  that*!n  fome  days 
a  peafant  will  find  gold  to  the  value  of  a  piftole,  and 
in  others  will  fcarcely  find  any. 

The  native  gold 'found  in  rivers  or  elfewhere  is  ne 
ver  perfectly  pure,  or  of  24  karats.  It  always  con 
tains  a  certain  quantity  of  allay,  which  is  generally 
filver.  The  gold  of  the  French  rivers,  according  to 
Mr  Reaumur's  trials,  was  found  to  be  from  18  to  22 
karats,  that  of  the  Ceze  being  the  loweft,  and  that  of 
the  Arreige  being  the  pureft. 

Although  gold,  however,  as  above  obfervecl  from. 
Macquer,  cannot  be  directly  dillblved  by  fulphur,  yet 
it  probably  may  be  mineralifed  by  the  intervention  of 
other  metallic  matters.  Thus,  although  no  proper 
ere  of  gold  exifts,  yet  it  is  found  in  feveral  mineral 
fubftances,  in  which  it  is  always  accompanied,  as. 
G  g  2  Cramer 


[     3*2    .3 

Cramer  affirms,  with  a  much  larger  quantity  of  ftlver  j 
to  which  hitter  metal  that  author  attributes  its  mine- 
ralifed  (late.  Tlie  minerals  containing  gold  are  blend, 
cupreous  and  arfcnical  pyrites*  ore  of  antimony,  cin 
nabar,  white  ore  of  arienic,  vitreous  and  other  filver 
ores,  and  the  lead-ore  called  galena. 

Gold  is  more  frequently  embedded  in  quartz  than 
in  any  other  matrix  ;  but  is  alfo  fc.und  in  limeftone 
and  in  hornblerd.  Gold  mines  are  in  general  very 
precarious,  as  they  do  nrt  form  regular  veins,  nor  is 
the  gold  unifoimly  diftributed  through  a  matrix. 

Becher  and  Cramer  think,  that  no  fand  is  entirely 
free  from  gold.  The  yelloxv,  red,  black,  and  violet- 
coloured  ferruginous  fands,  are  faid  to  contain  moil 
,  gold.  Mr  Hellet  relates,  that  in  1 1  eflays  of  one  kind 
of  fand,  from  a  quintal,  or  921,600  grains,  were  ob 
tained  each  time  iSrom  848  to  844  grains  of  noble 
metal,  exclufive  of  the  gold  which  remained  in  the 
fcoria  ;  and  that  of  the  metal  thus  obtained,  two-thirds 
were  gold,  and  the  remaining  third  was  filver.  He 
fays,  that  parcels  of  fand  taken  up  at  very  final! 
diftances  from  each  other  contained  very  unequal  pro 
portions  of  gold. 

The  gold  found  in  fands  is  generally  lefs  pure  than 
that  which  is  imbedded  in  a  folid  matrix.  Reaumur 
fays,  that  a  piece  of  gold,  weighing  448  ounces,  was 
ftiown  to  the  Royal  Academy  at  Paris,  which  was 
found  upon  eflay  to  have  different  finenefs  in  different 
parts  of  the  mafs. 

§  2.  Ores  and  earths  containing  gold  may  le  ejjaycd\)j 
the  methods  directed  for  the  extraction  of  gold  from 
large  quantities  of  thefe  auriferous  matters,  (fee  Part 
III.)  :  or  they  may  in  general  be  e flayed  by  being  fufed 
in  a  cupel  or  teft,  placed  under  the  muffle  of  an  effay- 
furnace,  or  in  a  crucible  placed  in  an  air  furnace,  with 
eight  or  ten  times  their  quantity  of  lead  if  they  be  eafily 
fufible,  and  with  a  larger  quantity  of  lead  if  they  he 
difficultly  fufible ;  and  by  fcorifying  the  caithy  matters, 

while 


[     3^3     ] 

while  the  lead  becomes  impregnated  with  the  noble 
metal.  Thefe  operations  are  entirely  fimilar  to  thoie 
employed  for  the  feparation  of  filler  from  its  ores  by 
precipitation  with  lead  ;  a  detail  of  which  fee  fubjoir.cd 
under  the  JeB'ion  ORES  of  SILVER,  \_Prcceffes  I.  III. 
IV.  V.  VI.].  Thefe  metals  are  afterwards  to  be  fe- 
parated  from  the  lead  by  cupeilation,  in  the  manner 
direcl'ed  in  the  article  ESSAY  (of  tks  value  of  Jil-ver 
and  of  gold.)  The  gold  is  then  to  be  feparated  from 
the  filver  by  the  procefles  deicribed  in  the  article 
PARTING. 

The  quantity  of  le;id  to  be  added  to  the  ore  in 
this  efiliy  mud  be  fuch  as  renders  the  fcoria  very  thin, 
that  the  whole  gold  may  be  imbibed  by  the  lead. 
Some  iron  ores  containing  gold  cannot  be  reduced 
into  a.  fcoria  fufficiently  thin  with  16  times  their 
quantity  of  lead,  unlefs  the  heat  be  at  the  fame  time 
conGderably  increafed.  When  the  ore  is  exceedingly 
refractory,  the  fcorification  ought  to  be  promoted 
by  adding  to  it  four  times  its  quantity  of  tartar,  twice 
its  quantity  of  nitre,  and  four  times  its  quantity  of 
litharge.  This  mixture  is  to  be  put  into  a  good  eflay- 
crucible,  and  covered  with  the  fea-ialt.  The  cru 
cible  is  to  be  fet  in  a  forge-hearth,  and  expofed 
gradually  to  heat,  till  the  fcoria  has  acquired  fuf- 
ficient  fluidity,  aiid  the  lead  has  imbibed  the  noble 
metal. 

See  the  methods  which  have  been  u fed  fir  effaying  aurl* 
fffous  fandsy  under  Pait  III. 

SECT.  II.     Ores  of  P latins. 

PLATIN.A  is  very  rare,  and  has  been  but  lately  dif- 
eovered.  As,  like  gold,  it  cannot  be  allayed  with 
iulphur  or  with  arfenic,.  probably  no  ore,  properly  fo 
called,  exifts  of  this  metal.  Accordingly  in  the  only 
mines  of  platina  which  we  knov\,  namely,  the  gold 
mines  of  Santafee  near  Carthagena,  the  platina  is  found 
native  like  the  gold,  and  in  its  metallic  ftate,, 

O  g  3,  SE.CT,, 


SECT.  III.     Ores  of  Sl/ver. 

§  i.  NEXT  to  gold,  filler  is  the  metal  moft  fre 
quently  found  in  its  metallic  (late,  that  is,  not  mine- 
rulifcd  by  fulphur  or  by  arfenic.  This  filver,  called 
alfo  native  or  virgin,  generally  affects  ibme  regular 
torm,  and  confifts  of  filaments  or  vegetations  of  va 
rious  figures.  It  is  found  in  form  of  plates,  of  fibres, 
or  of  grains,  or  crydallized.  It  lies  generally  in  quartz, 
flint,  fpar,  flate,  cobalt,  and  in  filver  ores.  It  is  fome- 
times  enveloped  in  a  thin  ftony  cruft.  It  is  generally 
allayed  with  Some  gold  :  but  filver,  like  all  the  other 
metals,  is  much  more  frequently  found  mineralised  by 
fulphur  and  by  arfenic. 

Three  principal  proper  ores  of  filver  are  known, 
which  are  very  rich,  but  very  rare.  Thefe  are, 

1.  The  vitreous  fiver  ore.     This   ore  has  no  deter 
minate  figure,  and  has  nearly  the  colour,  foftnefs,  and 
fufibility  of  lead.     It  is  very  heavy,  and  contains  three 
quarters  of  its  weight  of  pure  filver.     In  this  ore  the 
filver  is  mineralifed  by  fulphur  alone.  Some  expert  ar- 
tiits  imitate  it  very  well  by  combining  fulphur  with  fil 
ver  by  fuficn  in  a  crucible. 

This  ore,  according  to  Cronftedt,  is  eitl  er  in  form 
of  plates  or  of  fibres,  or  is  cryftallized,  or  has  no  de 
terminate  figure.  It  may  be  imitated  by  adding  about 
five  parts  of  fulphur  to  one  part  of  melted  filver  ;  in 
which  operation  moft  of  the  fulphur  is  confumed  ;  or 
it  may  be  imitated  by  expofing  a  plate  of  filver  red- 
hot  to  the  fumes  of  burning  fulphur. 

2.  The  hcrny  or  corn  ous  Jilver  ore.     This  ore  is  fo 
called  from  its  colour  and  femitranfparency,  by  which 
it  refembles  horn  or  colophony.     When  Suddenly  heat 
ed,  it    crackles,    as    altnoft    all    ores  do,    and  melts 
with  a  gentle  heat.     Two-thirds  of  it  are  iilver,  which 
is  mineralifed  by  fulphur  ard  arfenic.    This  ore  is  very 
rare.  Wallci  ius  fays,  after  Woodward,  that  it  is  found 
at  Johaun-GeorgeivStadt  in  Saxony, 

Corneous 


Corneous  ore  has  various  colours ;  white,  pearly, 
brown,  yellow,  greenifti,  or  reddifh.  It  is  foliated 
and  feniitraniparent.  It  is  fom^what  ductile,  and  fu- 
fible  with  the  rlame  of  a  candle.  When  heated,  it  emits, 
as  Wallerius  lays,  a  fulphureous  and  blue  flame,  and, 
accrrding  to  Cramer,  alf>  a  very  fmall  quantity  of  an 
arfenical  fume-  Wallerius  fays,  that  it  contains  two 
thirds  of  filver,  with  a  confiderable  quantity  of  ful- 
phur,  and  a  fmall  quantity  of  arfenic.  Lehman  thinks 
that  it  is  filver  united  with  a  little  arfenic.  But  Mr  Cron- 
ftedt  fays,  that  it  is  a  lima  correa,  or  filver  combined 
with  marine  acid  ;  ard  that  it  is  incapable  of  being 
decompofed  but  by  rubitances  which  can  unite  with 
that  acid.  This  latter  opinion  feems  to  be  the  m"ft 
probable  ;  as  the  ore,  according  to  its  dei'cription,  is 
firnilar  to  luna  cornea,  and  as  it  cannot  be  imitated  by 
any  mixture  of  ful  phur  and  of  arfenic  with  filver.  The 
blue  flame,  and  the  fmell  {lightly  arfenical,  which  are 
emitted  from  heated  corneous  ore,  are  alfo  obfervable 
from  every  combination  of  marine  acid  v/ith  a  fub- 
ftance  containing  phlogifton. 

3.  Red  filler  ore,  called  alfo  roficlare.  Its  colour 
is  more  or  lefs  red ;  it  is  fometimes  cryftallized,  very 
heavy,  and  is>  futible  like  the  abovementioned  ores. 
In  this  ore  the  (ilver  is  mineralifed  by  arfenic  and  by 
fulplur,  but  chiefly  by  the  former.  It  alfo  contains 
a  little  iron,  and  furnifhes  two-thirds  of  its  weight  of 
filver.  Its  red  colour  may  proceed  either  from  the 
iron  it  contains  ;  rr  from  the  mixture  of  arfenic  and 
fulphur  ;  or,  laftly,  from  the  p  tracular  manner  in 
which  the  arfenic  is  united  with  the  hlver,  an  example 
of  which  we  h,ive  in  the  red  precipitate  cf  filver  made 
by  the  neutral  arfenical  lalt. 

Red  Jifo-.r  ore  is  either  plared  or  f  lid,  or  cryftal- 
lifed,  and  frequently  femitraniparent.  Its  colour  is 
various,  ircm  a  dark  grey  to  a  deep  red,  according  to 
the  proportions  of  the  two  mineralifine  iubftances.  It 
crackles  and  breaks  in  the  fire,  exhales  an  arfenical 

fume, 


C     3«5     J 

fume,  and  is  readily  fuied.     It  is  found  generally  in 
quartz,  fpar,  cryftal,  horneblend. 

Befides  the  three  filver  ores  above  defcribed,  the 
following  ores  contain  filver  mixed  with  other  me 
tals. 

1.  Greyfther  ore.     This  contains  copper  and  filver 
mineralifed  by  avfenic  and  fulphur,  and  generally  more 
of  the  former  than  of  the  latter  metal ;  but  as  it  is  va 
lued  chiefly  for  the  filver,  it  has  been  generally  enume 
rated  among  ft  filver  ores. 

2.  White  fdver  ore  is  an  arfenical  pyrites  containing 
filver. 

3.  Black fifoer  ore  contains  fulphur,  arfenic,  copper, 
iron,  fometimes  lead,  and  about  a  fourth  part  or  filver, 
according  to  Wallerius. 

4.  Plumofe  Jiher  ore  is  white  or  black,  ftriated  like 
plumb-alum,  or  like  ore  of  antimony.     It  is  filver  mi 
neralifed  by  fulphur,  arfenic,  and  antimony. 

5.  Peel-blend.     In  this  blend  filver,  gold,  and  zinc, 
are  mineralifed  by  fulphur,  probably  by  intervention 
of  iron,  by  which  the  gold  and  zinc  are  rendered  ca 
pable  of  uniting  with  the  fulphur. 

6.  Silver  is  frequently  found  in  galena ;  and  fome 
times   in  martial  pyrites  ;  in  the  red  ore  of  arfenic  ;  in 
various  ores  of  copper,  lead,    tin,    iron,    and  efpecially 
eobah ;    in    Iknds ;    in  ye//otv    or  red  earths  /    in  black 
and  blue  bafaltes  ;  and    alfo  in  jlrata    of  Jl ones  which 
do  not  appear  externally  to  contain  any  mineral  fub- 
ftance. 

7.  Liquid fifoer  ore  or  guhr  of  filver,  is  a  grey  or  whi- 
tifa  liquid   mafs,  which  contains,  as  Wallerius  fays, 
either  native  filver,  or  ferae  fluid  fubftances  capable  of 
producing  it.     Mr  Cronfledt  mentions,  in  the  Swe- 
difh  Memoirs,  a  water  flowing  through   a  mine  in 
Norway    containing  filver.     Another  inftance  is  al 
fo  mentioned  of  a  (ilver  gtihr,  in  the  A%.  Erud.  UpfaL 
1720. 

8..  Mr 


C    367    J 

8.  Mr  Von  Jufti  pretends,  that  he  has  found  filver 
mineraltfed  by  an  alkaline  fubjlance ;  but  he  has  not 
fpoken  Sufficiently  diftinftly  concerning  it,  to  know 
whether  he  means  a  fa;ine  or  earthy  alkaline  mat 
ter.  Henckel  alfo  pretends,  that  by  treating  calcare 
ous  earth  or  certain  clays  with  pyrites,  filver  may  be 
obtained. 

§  2.  Ores  ofjilver  may  le  ejfaycd  by  the  fame  me 
thods  which  are  employed  for  the  extraction  of  that 
metal  from  large  quantities  of  ores ;  which  methods 
are  different,  and  fuited  to  the  different  qualities  of 
the  different  ores.  See  Part  III.  Or,  in  general,  ores 
and  earths  containing  filver  may  be  effayed  by  the  fol 
lowing  proceffec,  which  are  copied  from  Dr  Mortimer's 
Englith  edition  of  Cramer's  Art  of  ejjciying  metals.  Part 
ILProcefs  I. 

PROCESS    I. 

To  precipitate   Siher   by    meant    of  Lead  from  fufillt 
Om. 

"-Pouao  the  ore  in  a  very  clean  iron  mortar  into 
fine  powder :  of  this  weigh  one  docimafttcal  centner 
or  quintal,  and  eight  of  the  like  centners  of  granula 
ted  lead. 

"  Then  have  at  hand  the  docimaftical  teft,  which 
mud  not  as  yet.  have  ferved  to  any  operation  ;  pour 
into  it  about  half  of  the  granulated  lead,  and  fpread 
it  with  your  finger  through  the  cavity  of  it. 

"  Put  upon  this  lead  the  pounded  ore ;  and  then 
cover  it  quite  with  the  remainder  of  the  granulated 
lead. 

"  Put  the  teft  thus  loaded  under  the  muffle  of  an 
efTay-rurnace,  and  in  the  hinder  part  of  it ;  then  make 
your  fire,  and  increafe  it  gradually.  If  you  look  thro* 
the  holes  of  either  of  the  fliders,  you  will  foon  fee  that 
the  pounded  ore  will  be  raifed  out  of  the  melted  lead, 

and 


and  f\vim  upon  it.  A  little  after,  it  will  grow  clam 
my,  melt,  and  be  thrown  towards  the  border  of  the 
left :  then  the  furface  of  the  lead  will  appear  in  the 
middle  of  the  teft  like  a  bright  difc,  and  you  will  fee 
it  fmoke  and  boil  :  fo  foon  as  you  fee  this,  it  will  be 
proper  to  diminifh  the  fire  a  fin  all  matter  for  a  quar 
ter  of  an  hour  :  fo  that  the  boiling  of  the  lead  may 
almoft  ceafe.  Then  again,  increafe  the  fire  to  fuch  a 
degree,  that  all  may  turn  into  a  thin  fluid,  and  the 
lead  may  be  feen,  as  before,  fmoking  and  boiling 
with  great  violence.  The  furface  of  it  will  then  di- 
minifh  by  degrees,  and  be  covered  over  with  a  mafs 
offcorias.  Finally,  have  at  hand  an  iron  hook  ready 
heated,  wherewith  the  whole  mafs  muft  be  ftirred, 
efpecially  towards  the  border;  that  in  cafe  any  fmall 
parcels  of  the  ore  not  yet  diffolved  fhoukl  be  ad- 
Kerent  there,  they  may  be  brought  down,  taking 
great  eare  not  to  ilir  any  the  leait  thing  out  of  the 
teft. 

"  Now,  if  what  is  adherent  to  the  hook  during  the 
ftirring,  when  you  raife  it  above  the  teft,  melts  quick 
ly  again,  and  the  extremity  of  the  hook  grown  cold  is 
covered  with  a  thin,  fmooth,  (hining  cruit ;  it  is  a  fign 
that  the  fcorjfication  is  perfect ;  and  it  will  be  the 
more  fo  as  the  fald  cruft  adherent  to  the  hook  fh.ill  be 
coloured  equally  on  every  fide  :  but  in  cafe,  while  the 
fcorias  are  ftirred,  you  perceive  any  confiderable  clam- 
minefs  in  them,  and  when  they  adhere  in  good  quan 
tity  to  the  hook,  though  red-hot,  and  are  inequally 
tinged,  and  feem  dufty  or  rough  with  grains  inter- 
fperfed  here  and  there  ;  it  is  a  fign  that  the  ore  is  not 
entirely  turned  intJ  fcorias.  In  this  cafe,  you  muft 
with  a  hammer  ftrike  off  what  is  adherent  to  the  hook, 
pulverize  it,  and  with  a  laddie  put  it  again  into  the 
teft,  without  any  lofs  or  mixture  of  any  foreign  body, 
and  continue  the  fire  in  the  fame  degree  till  the  fcoria 
has  acquired  its  perfetfion  and  the  abovementioned 
qualities.  This  once  obtained,  take  the  teft  with  a 

pair 


C    369    ] 

pair  of  tongs  out  of  the  fire,  and  pour  the  lead,  toge 
ther  with  the  fcoria  fwimming  upon  it,  in^o  a  cone 
made  hot  and  rubbed  with  tallow.  Thus  will  the  firit 
operation  of  the  procefs  be  performed,  which  does 
not  commonly  indeed  laft  above  three  quarters  of  an 
hour. 

"  With  a  hammer  ftrike  the  fcorias  off  from  the  re- 
gulus  gror/n  cold,  and  again  examine  whether  they 
have  the  characleriftics  of  a  perfect  fccrifkation  ;  if  they 
have,  you  may  thence  conclude,  that  the  iilver  has 
been  precipitated  out  of  the  ore  turned  to  fcorias,  and 
received  by  the  lead. 

"  When  the  fccrifkation  lafts  longer  than  we  men 
tioned,  the  lead  at  laft  turns  to  fcorias  or  litharge,  and 
the  filver  remains  at  the  bottom  of  the  veffel :  but  tho 
lire  muft  be  moderately  fupplied,  and  the  yeflels  be 
extremely  good,  to  produce  this  effect ;  for  they  fel- 
dom  refift  the  ftrength  of  the  fcorias  long  enough  : 
fo  that  the  whole  fcorification  may  be  brought  to  an 
end  ;  which  has  afterwards  this  inconveniency,  that  the 
filver  is  cliffipated  by  grains  in  the  final!  hollows  of  the 
corroded  or,e,  and  cat;  hardly  be  well  collected  again, 
"when  the  ore  has  but  little  filver  ia  it.  Nay,  there  is 
dill  more  time  to  be  confurned  to  obtain  the  perfect 
deftruclion  of  the  lead,  by  means  of  the  combined 
aftions  of  the  fire  and  air,  becaufe  the  fcorias  fwim- 
ining  at  the  top  retard  it  confiderably. 

"  In  this  procefs,  the  fulphur  and  the  arfenic  of  the 
filver-ore,  when  the  ore  is  broken  fmall,  and  extended 
widely  in  a  fmall  quantity,  are  in  parteafily  diffipated 
by  the  fire,  and  in  part  a'oforbed  by  the  lead  ;  the 
lighter  part  of  which,  iwimming  upon  the  heavier,  be 
comes  very  clammy  by  means  of  the  fulphur  which  is 
in  the  ore  ;  but  -when  this  is  difljpated  by  the  violence 
of  fire,  it  turns  into  glafs.  or  fcoriaa:  but  when  arfe 
nic  is  predominant  in  the  ore,  the  plumbeous  part 
turns  immediately  into  a  very  penetrating  and  very  fu- 
fible  glttfs,  having  a  diifolving  efficacy,  unlefs  the  ar- 

Tenic 


t    370    3 

feme  lies  hidden  in  a  white  pyrites  or  cobalt.  For  this 
reafon,  the  fixed  part  of  the  ore,  which  is  no  filver,  is 
diflolved  by  that  glafs,  melts,  and  aflumes  the  form  of 
fcorias.  The  unmetallic  earths  and  the  pure  copper 
or  lead  ores  thereto  adherent  are  of  this  kind.  The 
filver  then  remains  immutable ;  and  being  freed  of  theie 
heterogeneous  bodies,  which  are  partly  diffipated  and 
partly  melted,  it  is  precipitated  and  received  by  the 
remaining  regulus  of  lead.  Therefore  this  procefs 
completed  by  three  diftinct  operations;  viz.  i.  By 
rcafting.  2.  By  fcorificadon.  3.  By  the  melting  pre 
cipitation  of  the  filver,  which  is  the  refult  of  the  two 
former  operations. 

"  The  ore  muft  be  pulverifed  very  fine,  in  order 
to  increafe  the  furface,  that  the  diffipation  of  the  vo- 
latiles  and  the  difiolution  by  litharge  may  be  fooner 
effected.  This  pulverifmg  muft  then  be  done  before  the 
ore  is  weighed,  becaufe  there  is  always  fome  part  of 
the  ore  adherent  to  the  mortar  or  iron  plate  on  which 
it  is  made  fine ;  which  part  being  loft,  the  operation 
is  not  exact.  Erker  was  in  the  right  when  he  pre- 
fcribed  eight  centners  of  lead  tor  the  fubduing  of  fu- 
fible  ores.  Neverthelefs,  it  muft  be  owned,  that  this 
quantity  is  fuperfloous  in  fome  cafes.  However,  as 
the  fluxibility  of  the  filver-ore  depends  upon  the  ab- 
fcnce  of  ftones,  pyrites,  &c.  it  is  eafy  to  fee,  that 
there  are  an  infinite  number  of  degrees  of  fluxibility 
\vhich  it  would  be  needlefs  to  determine  exactly,  and 
nioft  commonly  very  difficult  to  determine  by  the  bare 
fight.  Befides,  a  little  more  lead  does  not  render  the 
procefs  imperfect ;  on  the  contrary,  if  you  ufe  too 
fmall  a  quantity  of  lead,  the  fcorification  is  never 
completely  made.  Nay,  there  are  a  great  many  ores 
containing  fulphur  and  arfenic  in  plenty,  that  deftroy 
a  confiderable  quantity  of  lead  ;  fuch  are  the  red  fil- 
ver-ore,  and  that  wherein  there  is  a  great  deal  of  the 
Heel-grained  lead-ore.  If  the  fire  muft  be  fcmetimes 
diminished  in  the  middle  (£  the  procefs,  it  is  in  order 

4  to 


C     37<     ] 

to  hinder  the  too  much  attenuated  litharge,  which  is 
continually  generated  out  of  the  lead,  from  penetrating 
the  pores  of  the  teft,  and  from  corroding  it :  which  is 
eafily  done  when  the  fire  is  overftrong  j  for  then  the 
furface  of  the  veffel  which  is  contiguous  to  the  lead 
contracts  cavities,  or,  being  totally  confirmed  by  fmall 
holes,  lets  the  regulus  flow  out  of  it.  The  veffels  that 
are  moft  fubject  to  this  inconvenience  are  thofe  in 
the  materials  of  which  lime,  plafter,  and  chalk  are 
mixed.  Nay,  thefe  bodies,  which  are  in  their  nature 
refractory,  being  eroded  during  their  fcorification,  at 
the  fame  time  communicate  a  great  clamminefs  to  the 
fcoria  ;  fo  that  a  great  quantity  of  the  mafs  remains 
adherent  to  the  teft,  in  the  form  of  protuberances, 
when  you  pour  it  out ;  whereby  a  great  many  grains 
of  the  regulus  are  detained." 

PROCESS     II. 

TH  E  regulus  obtained  by  the  procefs  I.  contains  all 
the  iilver  of  the  ore,  and  the  unfcorified  part  of  the 
lead.  The  filver  may  be  afterwards  feparated  from  the 
lead,  and  obtained  pure  by  cupellat'wn  ;  which  procefs 
is  defcribed  under  the  article  ESSAY  (of  the  value  of 
Silver.) 


PROCESS     III. 

If  the  Jilver-ore  cannot  be  ivajhed  clean,  or  if  it  be  ren 
dered  refraftory  by  a  mixture  of  unmetallic  earths  andjlones* 
the  fcorification  of  thefe  earth y  matters  frequently  can- 
not  be  completed  by  the  procefs  I.  Cramer  therefore 
directs,  that  fuch  ores  (hall  be  treated  in  the  following 
manner. 

"  Bruife  the  ore  into  an  impalpable  powder,  by  grind 
ing  in  a  mortar  ;  to  a  docimaftical  centner  of  it  add  a 
like  quantity  of  glafs  of  lead  finely  pulverifed  ;  for  the 
more  exactly  thefe  two  are  mixed  cogether,  the  more 

H  h  eafily 


t    372   3 

cafily  the  fcorification  afterwards  fucceeds.  Pat  this 
mixture,  together  with  12  centners  of  lead,  into  the 
left,  according  to  procefs  I.  then  put  the  teft  under  the 
muffle. 

"  Make  firft  under  it  a  (Irong  fire,  till  the  lead  boils 
very  well,  when  you  fee  it  fo,  diminiih  the  violence 
of  the  heat,  as  was  directed  in  the  firft  procefs ;  but 
keep  it  thus  diminifhed  a  little  longer :  then,  finally, 
again  increafe  the  fire  to  fuch  a  degree,  till  you  per 
ceive  the  figns  of  a  perfect  fcorification  and  fufion.  See 
t/j:  w/jote  prr.cefs  I.  Now  this  procefs  lafts  a  little 
longer  than  the  foregoing,  and  requires  a  greater  fire 
towards  the  end. 

"  It  fometimes  happens  that  a  very  refractory  ore 
cannot  be  dilfolved  by  litharge ;  and  that  a  mafs, 
which  has  the  clamminefs  of  pitch,  fwims  upon  the 
regulus  and  upon  the  fcorias  themfelves  which  are  al 
ready  fubdued  in  part :  when  you  fee  this,  Ihut  the 
vents  of  the  furnace  to  diminifh  the  firg  ;  then  gently 
touch  this  refractory  body  with  a  fmall  iron  cold  hook 
to  which  it  will  immediately  ftick  ;  take  it  off  foftly, 
not  to  lofe  any  thing;  pound  it  into  a  fine  powder, 
adding  a  little  glafs  of  lead,  and  put  it  again  into  the 
teft;  then  continue  the  fcorification  till  it  is  brought 
to  its  perfection.  But  you  mud  always  examine  the 
fcoria  of  your  refractory  ore,  to  fee  whether  there 
may  not  be  fome  grains  of  regulus  difperfed  in  it ;  for 
fometimes  the  fcorias  that  grow  clammy  retain  fome- 
thing  of  the  metal;  which  if  ycu  fufpect,  pound  the 
fc<  nas  into  a  fine  duft,  and  thus  the  grains  of  metal 
\vill  appear  if  there  are  any  left,  becaufe  they  can  never 
be  pounded  fine.  The  (liver  is  feparated  from  this 
regulus  by  cupelling,  as  in  Prrcefs  II. 

"  All  earths  and  (tones  are  refractory  in  the  fire  ; 
for  although  fome  of  them  melt  naturally  in  the  fire, 
as  thofe  that  are  verifiable  do  ;  neverthelefs  all  the 
others,  a  very  few  excepttd,  melt  much  more  diffi 
cultly  than  metals,  and  never  become  fo  thin  in  the 

fufion 


E     373     1 

full  on  as  is  required  for  the  fufficient  precipitation  of . 
a  precious  metal.     But  litharge  itfelf  does  not  con 
veniently  diilolve  thefe  refractory  matters  by  the  help  ; 
of  fire  alone,  unlefs  you  add  fome  mechan;cal  mixture 
to  them  ;  for  the  very  moment  the  faid  litharge  pene 
trates  through   the  interftices  of  the  refractory  ore, 
and  begins  to  difiblve  it,  a  tenacious  mafs  is  produced, 
which  hardly  admits  any  farther  dilution  by  the  li-  , 
tharge.     You  may  fee  it  plain,  if  you  make  coloured 
glaffes  with  metallic  calces  :  if  you  pour  carelefsly  upon 
them  a  calx  that  gives  a  colour,  you  will  never  obtain 
that  they  may  be  equally  dyed  on  every  fide,  even  al-  . 
though  you  fh<  uld  torture  them  for  whole  days  toge 
ther  in  a  great  fire.  Nay,  glafs  already  made  can  never 
be  diluted  by  only  pouring  falts  and  litharge  upon  it.  . 
Wherefore  you  muft  ufe  the  artifice  of  glafs-rnakers, 
who,  in  the  making  of  the  mod  perfect  glailes,  take 
great  care,  before  they  put  the  fpecies  of  their  ingredi 
ents  into  the  fire,  to  have  a  mechanical  mixture  pre 
cede,  or  at  leaft  accede,  during  the  fufion  itfelf,  which 
is  done  here  by  pounding  glafs  of  lead  mixed  with  the  • 
ore  ;  but  if  you  think  that  your  glafs  of  lead  is  not  fufH- 
ciently  fufible,  you  may  add  to  it  litharge  melted  firlt, 
and  then  pounded  into  a  fine  powder. 

"  As  this  fcorification  requires  a  longer  and  a  greater 
fire  than  the  foregoing,  and  as  a  greater  quantity  of 
litharge  is  moreover  requifite  to  fubude  the  refractory 
fcoria;  it  is  eafy  to  fee  why  a  much  greater  quantity 
of  lead  muft  be  ufed  here  than  in  Procefs  I. ;  and, 
although  lefs  lead  is  often  fufficient,  it  is  neverthelefs 
proper  always  to  ufe  the  greateft  quantity  that  can  be 
neceifary  ;  left,  for  inftance,  it  fhould  be  necefTary  to 
try  fo  many  times  the  lead  alone  to  make  it  evident  how 
much  filver  the  lead  when  alone  leaves  in  the  cuppel. 
Nor  need  you  fear  left  any  thing  of  the  filver  be  taken 
away  by  the  lead,  provided  the  cuppels  be  good,  and 
the  cuppelling  duly  put  in  the  execution  ;  for  you  can 
hardly  collect  a  ponderable  quantity  of  filver  out  of  the 

c'olle&ed 


C     374     3 

collected  fume  of  the  lead,  which  rifes  during  the 
cuppelling,  as  well  as  out  of  the  litharge  that  is  with 
drawn  into  the  cuppeL" 

PROCESS      IV. 

If  the  ore  le  rendered  refractory  ly  p\rites,  Cramer 
directs  that  the  filver  fhould  be  precipitated  by  lead 
in  the  following  manner.  (Art  of  AJfa^in^  Part  II. 
prcc.  4.) 

"  Break  your  ore  into  a  rough  powder,  and  put  a 
centner  of  it  into  the  tefti  put  upon  this  another  teft 
in  the  manner  of  a  tile  ;  put  it  under  the  muffle  hardly 
red  hot  :  increafe  the  fire  by  degrees.  There  will 
always  be  a  crackling  :  which  being  ended,  take  away 
the  upper  teft  ;  for  when  the  veflels  have  been  red- 
hot  about  one  minute,  the  ore  ceafes  to  fplit.  Leave 
the  ore  under  the  muffle  till  the  arfenic  and  the  ful- 
phur  are  for  the  mod  part  evaporated  ;  which  you 
will  know  from  the  ceifation  of  the  vifible  fmoke,  of 
the  fmell  of  garlic,  or  the  acid  ;  then  take  away  the 
teft,  and  leave  it  in  a  place  not  too  cold,  that  it  may 
c col  of  itfelf. 

^  PoxiT  onf,  without  s.ny  d&Spatteo,  the  roafte<l 
ore,  and  with  a  kriiie  take  away  what  is  adherent  to 
the  veflel ;  pound  it  to  a  mod  fubtile  powder,  and 
grind  it  together  with  an  equal  weight  of  glafs  of 
lead  ;  and,  "finally,  fcorify  the  whole  collected  ore  in 
the  fame  teft  wherein  the  tefting  was  made,  unlefs  it 
has  contracted  chink?,  as  was  described  in  Procefs  III. 

"  Remarks.  Yellow  pyrites-ores  contain  a  very 
great  quantity  of  fulphur,  even  greater  than  is  necef- 
fary  to  faturate  the  metal  that  lies  hidden  in  them. — 
For  which  reafon  this  fuperfluous  fulphur  diffipates  in 
a  middling  fire  ;  but  if  it  had  been  mixed  with  lead, 
it  would  have  rendered  it  refractory,  nor  could  it  af 
terwards  be  diffipated  from  it  without  a  confiderable 
detraction  of  the  lead.  The  white  arfenical  pyrites 

turn 


C     375    J 

•  i 

turn  alfo  a  great  quantity  of  lead  into  glafs,  on  Ac 
count  of  the  abundance  of  the  arfenic  they  contain. 
For  which  reafon  theie  ores  muft  be  previoufly  roafted, 
that  the  fulphiir  attd  arfenic  may  be  diflipated.  Nor 
need,  you  fear  left  any  part  of  the  filver  be  carried 
away  with'  the  arfenic  ;  for  when  arfenic  is  feparated 
from  any  fixed  body,  by  a  certain  degree  of  fire,  it 
carries  nothing  of  that  body  away  with  it." 

PROCESS     V. 

Stiver  may  be  precipitated  from  its  ore  ly  cupellailon  only, 
in  the  following  Procefs,  given  by  Cramer.      [Art 
Part  II.   Proc.  9.] 


"  Pound  one  centner  of  ore  ;  roaft  it  in  the  man 
ner  directed  in  the  laft  proceis  j  beat  it  to  a  rnoft 
fubtle  powder,  and  if  it  melts  with  difficulty  on  the 
iire,  grind  it  together  with  one  centner  of  litharge, 
which  is  not  necellary  when  the  ore  melts  eafily  :  then 
divide  the  mixture  or  the  powder  of  the  ore  alone  into 
five  or  fix  parts,  and  wrap  up  every  one  of  them  feve- 
rally  in  fuch  bits  of  paper  as  can  contain  no  more  than 
this  fmall  portion. 

"  Put  a  very  large  cuppel  under  the  muffle  ;  roaft 
it  well  firft,  and  then  put  into  it  fixteen  centners  of 
lead  :  when  the  lead  begins  to  fmoke  and  boil,  put 
upon  it  one  of  the  fa:d  portions  with  the  fmall  paper 
it  was  wrapt  up  in,  and  diminifh  the  fire  immediately^ 
in  the  fame  manner  as  if  you  would  make  a  fcorifica- 
tion  in  a  teft,  but  in  a  leiler  time.  The  fmall  paper, 
which  turns  prefently  to  allies,  goes  oft  of  itfelf,  and 
does  not  fenfibly  increafe  the  mafs  of  the  fcorias.  The 
ore  proceeding  therefrom  is  caft  on  the  border,  and 
turns  to  fcorias  very  foon.  Jncreafe  the  fire  asrain  im 
mediately,  and,  at  the  fame  time,  put.  another  por 
tion  of  the  ore  into  the  cuppel,  as  was  juft  now  faid. 
The  fame  eiTe&s  will  be  produced.  Go  on  in  the 
H  h  3  fume 


C    376    ] 

fame  manner,  till  all  the  portions  are  thrown  in  and 
confumed  in  the  lead.  Finally,  deilroy  the  remaining 
lead  with  a  ftronger  fire. 

"  The  filver  that  was  in  the  ore  and  in  the  lead 
will  remain  in  the  cuppel.  If  you  deduct  from  it  the 
bead  proceeding  from  the  lead,  you  will  have  the 
weight  of  the  filver  contained  in  the  ore.  If  the  ore 
employed  was  eafy  to  be  melted,  all  the  fcoria  vaniflies; 
but  if  it  was  refractory  or  not  fufible,  all  the  fcoria 
does  not  always  go  away,  but  there  remains  fome- 
thing  of  it  now  and  then  in  the  form  of  duft.  A  great 
many  ores  and  metals  may  be  tried  in  this  way,  ex 
cept  only  fuch  as  fplit  and  corrods  the  cuppels. — 
Tbere  are  likewife  fome  of  them  which  muft  be  pre- 
vioirfly  prepared  in  the  fame  manner  as  is  required 
to  render  them  fit  for  going  through  a  fcorification. — 
See  the  for  tgo'mg  Proceffes. 

"  Remarks.  The  ore  thrown  at  feveral  times  up 
on  lead  boiling  in  a  cuppel  may  be  diflolved  without 
the  foregoing  fcorification  ;  but  this  is  very  far  from 
having  an  equal  fuccefs  with  all  kinds  of  ores  ;  for 
there  are  ores  and  metals  which  refifl  very  much 
their  diifolution  by  litharge  ;  and  which  being  on  this 
account  .thrown  on  the  border,  are  not  fufficiently 
diflolved ;  becaufe  the  litharge  fteals  away  foon  into 
the  cuppel.  Neverthelefs,  there  are  fome  others  which 
varnfh  entirely  by  this  method,  except  the  filver  and 
gold  that  was  contained  in  them. 

"  A  previous  roafting  is  neceiTary,  firft,  for  the 
reafons  mentioned,  and  then  tecaufe  the  ore  thrown 
upon  boiling  lead  fhould  not  crackle  and  leap  out ; 
for,  having  once  pafTed  the  fire,  it  bears  the  moft  fud- 
<Jen  beau" 


PROCESS 


C     377     1 

PROCESS     VI. 

Sifos r  may  le  precipitated  out  of  tie  Jame  bodies  as  ^?rc 
mentioned  in  the  foi  >  going  procejjes  by  fcorsjicaiiun  in  a 
irucib.e.  [^Craner,  Proc.  15. _j 

"  The  body  out  of  which  you  intend  to  precipitate 
filver  muit  be  previoufly  prepared  lor  a  fcorification 
by  pounding  and  r<  ailing,  as  mentioned  in  the  tormer 
pioceffes.  Then  in  the  fume  manner,  and  with  the 
fame  quantity  of  lead,  put  it  into  a  crucible  itrictly 
ex.iniint-d,  that  it  be  en- ire,  folid,  not  fpeckled  with 
black  fp  ts,  like  the  fcoria  of  iron,  efpecially  at  its 
interior  parts,  and  capable  of  containing  three  times 
as  much.  Add  befides  glals  gall  and  common  fait, 
bo:h  very  dry,  and  enough,  that  when  the  whole  is 
rml.e^t  the  fairs  may  fwim  at  top  at  the  height  cf 
about  halt  an  inch. 

"  Put  the  crucible  thus  loaded  in  a  wind-furnace  ; 
fhiU  it  clofe  with  a  tile;  put  coals  round  it,  but  net 
higher  thvm  the  upper  border  of  the  crucible.  Then 
light  them  with  burning  coals,  and  increafe  the  fire 
till  the  whole  melts  very  thin,  which  will  be  done  by 
a  n.  dJiing  fire,  maintained  always  equal,  and  never 
gri-'er;  leave  it  thus  for  abc  ut  one  quarter  of  an 
hoi'-,  that  the  fcorification  may  be  perfectly  made. 
Take  oil  the  tile  and  ftir  the  mafs  with  an  iron  wire, 
and  a  little  after  pour  it  out  into  the  mould.  When 
the  regulus  is  cleaned  from  fcorias,  try  it  in  a  teft  by 
cuppelling  it. 

*'  Remarks.  The  fcorification  of  any  ore  what 
ever,  or  of  ar.y  body  fetched  out  of  ores,  may  indeed 
be  reade  by  this  apparatus,  as  well  as  in  a  telt  under 
a  muffle  :  but  it  ferves  chiefly  to  the  end  that  a  greater 
quantity  of  metal  may  be  molted  £om  it  with  profit. 
cu  may  put  many  common  pounds  of  it  at  one 
fii'^;e  time  into  the  crucible;  but  then  you  need  not 
cbierve  the  preportion  of  lead  prefcribed  m  the  fore 
going 


i    378    3    ' 

going  procefs;  nay,  a  quantity  of  lead  two  or  three 
times  lefs  is  fufficient,  according  to  the  different  qua 
lities  of  the  object.  But  the  mafs  will  certainly  he 
fpl't,  unleis  you  choofe  a  very  good  crucible  ;  for  there 
is  no  veflel  charged  with  litharge  that  can  bear  a 
ftrong-  tire  having  a  draught  of  wind,  without  giving 
way  through  it  to  the  litharge, 

"  You  add  glafs-gall  and  common  fait,  that  they 
may  forward  the  fcorificauon,  by  f\vinirmn<?;  at  top  ; 
for  the  refractory  fcoria  rejected  by  the  litharge,  and 
adhering  between  this  and  the.falts  that  i'vim  at  top, 
is  foon  brought  to  a  flux,  and  the  precipitation  of  the 
filver  is  thereby  accelerated.  Thty  alib  hinder  in  3, 
rr.-anner  a  fmall  burning  coal  fallen  into  the  crucible, 
from  fetting  the  litharge  a  boiling,  which  troubles 
the  operation  ;  for  the  litharge  or  gla  s  of  lead,  efpe- 
cially  that  which  is  made  without  any  addition,  1!> 
foon  as  the  phL  gifton  gets  into  it,  rifes  into  a  foamy 
mafs,  confiding  ot  a  multitude  of  fmall  bubbles  very 
difficult  to  be  confined,  unleis  the  phlogifton  be  en 
tirely  confurred,  and  the  litharge  reduced  to  lead, 
which  fom crimes  rife*;  above  the  border  of  the  veffel." 

The  corneous  ere,  if  it  really  be,  as  Cronftedt  fays, 
a  luna  con  <:a,  ought  to  be  treated  in  feme  of  the  me 
thods  directed  for  the  reduction  of  luna  cornea.  See 


PROCESS     VII. 

Slfaef  atid  gold  may  le  extracted  from  their  ores  ly  mercury, 

A  new  method  of  extracting  the  precious  metals  by 
means  of  amalgamation  with  mercury  has  lately  been 
introduced  into  Germany.  The  attraction  between 
thefe  has  indeed  been  known  from  the  moft  remote 
antiquity  ;  Vitrivius  inform  us,  that  by  this  means 
gold  might  be  recovered  from  embroidery  and  old 
cloaths  5  ajid  Pliny  mentions  the  gilding  of  brafs  and 

other 


C    379    3 

ether  metals  by  the  fame  means.  From  time  imme*' 
inoiial  mercury  has  been  made  ufe  of  in  the  ftrcaming- 
for  gold,  in  order  to  purify  and  collect  together  the 
gold  duft  which  is  difperfed  in  the  fands ;  and  almoft 
a;l  nations  who  practice  this  ufe  the  fame  procefr.  The 
gold  fand,  after  being  wafhed,  is  r.rh.u»-ated  with  quick- 
Silver,  and  the  fuperfluoiis  metal  feparated  by  ftrain- 
ing  through  leather.  By  the  mineis  it  was  ufed  in  a 
fimilar  manner  ;  the  ftones  containing  gold  being  fi-ft 
pound°d  and  then  triturated  in  mills  along  with  the 
mercury.  But  it  was  foon  found,  that  in  thefe  mills 
there  was  a  large  quantity  left  behind  in  the  refiduum, 
fo  that  it  was  neceflary  to  fubject  what  was  left  to  the 
action  of  fire  ;  on  which  account  the  mills  were  deem 
ed  unneceffary,  and  are  now  almoft  every  where  dif- 
ufed.  The  procefs  of  extracting  gold  and  filver  by 
amalgamation,  however,  was  looked  upon  to  be  eflen- 
tially  deficient,  by  reafon  of  an  opinion  which  prevailed 
among  the  chemifts,  that  mercury  could  not  diflolve 
either  of  thefe  metals  except  in  their  pure  and  perfect 
ftate  ;  whence  it  was  fuppofed,  that  a  great  quantity 
which  fire  could  have  extracted  was  left  by  the  mer 
cury.  This  opinion  was  fupported  by  the  moft  cele 
brated  metallurgies,  as  Schlutter,  Gellert,  Wallerius, 
and  Cramer ;  whence  it  became  generally  believed, 
that  amalgamation  would  never  aniwer  in  great  opera 
tions.  But  of  late  Baron  Inigo  Born  has  not  only  de 
mon  ftrated  that  this  can  be  done  to  great  advantage, 
but  has  actually  introduced  it,  notwithftanding  that 
fome  difficulties  were  thrown  in  his  way.  The  fol 
lowing  is  an  account  of  the  methods  which  have  been 
practifed  for  feparating  gold  and  filver  from  their  ores 
by  means  of  quickfilver. 

This  procels  was  introduced  into  fome  of  the  mines 
of  Mexico  in  1566  by  Don  Pedro  Fernandez  de  Ve- 
lafco,  and  in  1571  into  fome  of  thofe  of  Peru  by  the 
fame  perfon  ;  and  from  thence  it  quickly  fpread  thro* 
all  the  mines  in  the  fouth  and  north-eaft  parts  of  Ame 
rica, 


C 

nca,  infomuch  that  it  is  almoft  the  only  method  ufed 
in  that  part  of  the  world  for  extruding  theie  metals. 
The  richer  ores,  however,  are  purified  by  fufion  with 
lead;  and  our  author  informs  us,  that  ft  rmerly  the 
poorer  kind  of  ores  were  certainly  L.roxvn  away,  and 
when  the  method  cf  amalgamation  as  introduced  into 
Peru,  the  old  hairows  were  ieaiched  for  the  ores  which 
had  been  rejected  as  ufelefs,  but  were  now  put  to  the 
quickfilver. 

In  the  year  1588,  Don  Juan  de  Corduba,  a  Spa 
niard,  applied  to  the  court  of  Vienna,  propofmg  to 
extract  filver  from  its  ores,  whether  poor  or  rich, 
by  mercury,  and  in  a  fhort  fpace  of  time.  He  made 
fome  experiments  upon  different  kirds  of  ore,  which 
on  a  fmall  fcale  fu receded  very  well,  but  on  attempt 
ing  it  with  20  quintals  of  it  he  failed  ;  and  as  Lazarus 
Erker,  who  was  en  pl<  yed  to  give  in  a  report  concern, 
ing  it,  difapproved  of  the  method,  it  was  net  purfued 
any  farther.  The  reafons  alleged  in  Baron  Born's 
book  f <  r  this  failure  are,  that  he  did  not  calcine  his 
ore  :  that  he  did  not  uie  any  fait ;  and  that  the  weather 
was  too  cold  ;  thr.ugh  this  laft  circumftance  might  have 
been  remedied  had  Corduba  attended  to  it. 

Another  Latin  and  anonymous  account  of  the  mode 
of  amalgamation  is  preferved  armngthe  records  of  the 
aulic  chamber.  It  is  directed  to  the  emperor,  but  the 
year  in  which  it  was  written  is  not  mentior  ed.  Ac 
cording  to  the  account  given  by  the  author  of  this  pa 
per,  he  had  examined  the  mines  of  Guatimala  in  New 
Spain,  and  made  fome  ufeful  regulations  for  them. 
He  directs  the  ore  to  be  calcined  in  furnaces  like  lime 
kilns,  the  fire  being  kept  up  according  to  the  nature  of 
the  ores,  after  which  they  are  to  be  reduced  to  powder 
in  mills  or  ftamps.  The  pulverifed  matter  is  then 
pafled  through  fine  iron  fieves,  and  put  into  earthen  or 
copper  veflels  by  10  or  20  quintals  at  a  time  ;  more 
or  lefs  fait  being;  mixed  with  it  according  to  circum- 
ftances.  The  light-coloured  ore  requires  50  Ib.  to 

every 


C    3"    3 

every  thoufand,  and  the  darker  fomewhat  more.  To 
this  mixture  are  to  be  added  five  pounds  of  dry  tartar, 
two  pounds  of  pulverized  horn,  and  three  pounds  of 
brick-duft.  Some  kinds  of  ores  require  but  a  fmall 
quantity  of  thefe  additions. 

After  the  mixtures  are  put  into  the  boilers,  as  much 
water  is  added  as  will  make  the  whole  of  the  confidence 
of  pafte  moderately  thick;  the  vefTels  mull  be  expofed  to 
funlliine,  or  kept  in  a  place  warmed  artificially,  adding 
more  water  when  the  matter  begins  to  dry;  and  it 
muft  be  ilirred  up  three  or  four  times  a-day.  At  the 
expiration  of  three  or  four  days,  various  colours  appear 
upon  the  furface.  After  this  15  Ib.  of  brimftone  is  to 
be  added  to  every  thoufand  pounds  of  ore,  and  the 
whole  worked  over  again  ;  but  this  addition  is  by  the 
baron  corifidered  as  quite  fnperfluous.  Laftly,  loolb. 
or  lefs  of  quickiilveris  added,  according  to  the  nature 
of  the  ore ;  the  whole  mafs  is  carefully  worked  over, 
and  left  at  reft  for  10  hours.  A  fire  muft  next  be 
kindled  under  the  boiler,  and  the  matter  it  contains 
triturated  or  ftirred  for  two  days  together  ;  keeping  it 
always  fufficiently  diluted  by  a  proportional  quantity 
of  water.  It  is,  laftly,  allowed  to  reft  for  12  hours, 
and  then  dried. 

When  this  operation  is  fuccefsfully  performed,  if 
the  ores  be  rich,  par  tides  of  amalgam  will  be  feen  in 
it:  thefe  are  collected,  waflied  out,  and  kept  for  fur 
ther  ufe,  the  leavings  being  carried  to  a  place  fit  for 
walhing  over.  This  place  ought  to  be  on  the  flope  of 
an  hill,  where  a  kind  of  pit  is  dug  out  and  lined  with 
brick  and  mortar,  and  ought  to  be  large  enough  to 
contain  25  quintals.  A  ftrearn  of  water  is  then  made 
to  run  up^n  it,  and  the  matter  ftirred  without  inter- 
mifiion.  The  fuperfluous  water  runs  over  the  rim  of 
the  pit,  and  carries  off  the  lighter  ftony  and  earthy 
particles,  the  heavy  amalgam  remaining  at  bottom. 
This  is  then  to  be  mixed  with  the  fmall  clots  already 
mentioned,  which  were  taken  out  of  the  mafs  origi 
nally 


t   3«^   3 

nally,  atid  prefTed  through  a  cloth  made  of  hemp  cr 
coarfe  linen.  The  quickfilver,  which  comes  through 
clean,  is  kept  for  farther  ufe  ;  the  remainder  diftilled  off 
in  proper  veflels,  and  the  remaining  filver  melted  into 
ingots.  B>  th;s  method  it  is  faid  that  even  very  poor 
ores  are  worked  to  advantage,  the  expence  being  very- 
moderate. 

The  following  method  of  extracting  gold  from  its 
ores  is  very  much  recommended  by  our  author :  '*  The 
auriferous  land,  which  contains  gold  grains  and  gold- 
duft,  is  concentrated  by  wafhing;  and  without  any 
calcination  goes  to  the  abovtirientioned  waihing-pit, 
which  for  this  purpofe  need  not  be  fo  laige.  On  its 
upper  part  is  fixed  a  fquare  launder,  about  12  feet 
long,  covered  in  the  bottom  with  a  woollen  cloth,  in 
order  to  retain  ai:y  part  of  the  gold-duft  which  may  be 
carried  over  with  the  water  and  ftuff  gently  ithred  in 
the  pit.  When  the  water  carries  off  no  more  mud,  but 
runs  clear,  the  farther  fupply  is  to  be  flopped ;  the 
water  in  the  pit  is  pumped  or  taken  out  wit.i  buckets  ; 
the  coarfer  fand  in  the  bottom  is  leparated  or  fcraped 
off  by  hands :  and  the  finer  heavieh1  land  at  the  bottom 
is  mixed  with  quickfilver.  Then  it  is  fqueezed  through 
a  piece  of  cl^th  ;  the  quickfilver  comes  off  vvithoutany 
gold,  which  feparated  from  the  fand  remains  as  an 
amalgam,  and  is  pure  after  the  remaining  quickfilver 
has  been  evaporated.  The  fand  and  heavier  duft  re 
maining  on  the  launder  is  wafhed  and  treated  in  the 
fame  manner. 

"  The  auriferous  ores  and  loadftones,  however, 
which  rife  from  different  mines,  are  calcined  like  filver 
ores,  more  or  lefs  as  the  nature  ol  their  matrixes  will 
direct.  Then  they  are  ground  and  rifted  ;  and  the  au 
riferous  ftuff,  thus  prepared,  is  put  into  heaps,  expo- 
fed  to  the  funlhine,  ani  worked  and  turned  about  for 
three  or  four  days.  It  requires  no  fait.  Afterwards 
fulphur,  and  atlaft  quickrtlver,  are  added  and  mixed 
\vith,  it.  There  is  no  occafion  for  fire  under  the  veffel 
4  in 


in  winch  it  is  triturated,  except  in  winter;  and  two 
Jays  after,  though  not  dried,  it  is  immediately  carried 
to  the  wafliing  pit,  and  treated  like  the  amalgam  of 
filver. 

"  This  method  of  extracting  gold  and  filver  is  fo 
certain  and  fafe,  that  when  other  method*;  of  amalga 
mation  extract  only  one  ounce  of  gold  and  filver,  this 
produces  three  or  four  from  the  pooreft  ores  in  a  fhor- 
ter  time  and  with  leis  expence." 

P.  Jofeph  Acofta  tells  us,  that  at  Potofi  6000  or  7000 
quintals  of  quickfilver  are  annually  confumed  in  the 
drefling  of  the  ore,  not  to  mention  what  is  recovered 
from  the  leavings  of  the  firft  wafhing.  Thefe  leavings, 
called  lamas t  are  burnt-in  particular  furnaces  in  order 
to  extract  the  remaining  quickfilver;  and  there  are 
upwards  of  50  fuch  furnaces  near  Potofi  and  Tarapa- 
ja.  The  ore  refined  there  amounts,  according  to  the 
bed  information,  to  the  immenfe  quantity  of  300,000 
quintals.  Only  about  2000  quintals  of  the  quickfilver 
are  recovered,  which  (hows  alofs  of  about  two  pounds 
of  quickfilver  on  every  quintal  of  ore.  The  ores  are 
of  different  natures,  and  in  proportion  to  the  filver 
they  contain  require  more  or  lefs  quickfilver.  That 
which  contains  moft,  requires  naturally  the  greatefl 
quantity  of  quickfilver  ;  though  feme  of  the  workmen 
pretend  that  there  is  a  kind  which  contains  very  little 
filver,  and  yet  requires  a  great  deal  of  mercury  :  but 
whether  this  be  owing  to  the  ignorance  of  the  work 
men,  or  to  the  mercury  being  abforbed  by  feme  other 
matter,  is  not  generally  known,  The  ore  is  firf'c  pul 
verifed  in  mills,  and  then  patted  through  iron  or  brafs 
lleves.  The  mills  will  grind,  when  properly  regulated, 
.30  quintals  in  the  fpace  of  24  hours.  The  pulverifcd 
matter  is  put  into  heaps  in  the  open  air,  and  fait  is 
mixed  with  it  in  the  proportion  of  5  to  50  quintals  of 
the  ore,  in  order  to  macerate  and  cleanfe  it  of  its  im 
purities,  that  the  quickfilver  may  the  more  readily 
amalgamate  with  the  m^tnl.  Upon  thefe  heaps,  and 
I  i  while 


C     3*4     ] 

while  they  are  {Hiring,  the  quickfilver  is  preffed 
through  a  cloth.  Before  the  invention  of  fire-places, 
the  ore  was  repeatedly  kneaded  with  quickfilver  in 
wooden  trough's  and  formed  into  large  round  maf- 
fes,  which  were  left  in  that  form  for  two  days  ;  after 
which  they  were  worked  again,  until  the  metals 
appeared  to  be  embodied  together,  which  took  from 
9  to  20  days ;  but  it  was  afterwards  fougad  that 
heat  aflifted  the  operation  fo  far,  that  by  means  of 
proper  ovens  the  fame  might  be  accompliihed  in  five 
or  fix  days.  When  the  quickfilver  has  taken  up  the 
filver,  and  wholly  feparated  it  from  its  matrix  the  lead 
and  the  copper,  the  ovens  are  opened,  the  matter  is 
taken  out,  and  the  quickfilver  expelled  and  recovered 
in  the  following  manner.  The  mixture  is  put  into  wa 
ter  troughs,  and  ftirred  therein  by  means  of  mills  and 
water-wheels,  by  which  the  earthy  and  extraneous  par 
ticles  are  waflied  away,  and  the  amalgam  fettles  at  the 
bottom.  The  fediment  looks  like  fand.  It  is  further 
wafhed  over  in  flat  plates,  and  perfectly  cleanfecl ;  what 
goes  off  with  the  water  is  collected  for  further  ufe  un 
der  the  name  of  relates.  When  the  amalgam  is  be 
come  clean  and  bright  by  this  method,  it  is  put  into 
a  cloth  and  fqueezed  out.  This  uncombined  quick 
filver  runs  off,  and  the  remaining  body  of  amalgam 
contains  five  parts  of  quickfilver  and  one  of  folid  metal. 
It  is  made  into  mafTes  named  pinnas,  having  the  form 
of  a  fugar  loaf,  hollow  within,  and  weighing  about 
100  pounds.  They  are  expofed  to  a  ftrong  fire  in 
order  to  expel  the  quickfilver,  after  being  put  into  pots 
covered  with  earthen  heads.  The  filver  ftill  appears 
in  the  form  of  amalgam,  but  is  reduced  to  one  fixth  of 
the  former  weight.  Its  texture  is  fpongy,  and  the 
quality  of  the  metal  fo  fine,  that  the  filver-fmiths  can 
not  work  it,  neither  can  it  be  formed  into  coin,  with 
out  an  alloy.  Baron  Born  obferves,  however,  that  it 
is  only  cold  amalgamation  which  produces  filver  of 
fuch  uncommon  finenefs ;  by  hot  amalgamation  it  is 

generally 


C    385    3 

generally  alloyed  with  copper,  which  cannot  be  parted 
from  it  without  cupellation. 

The  moft  circumftantial  account  of  the  amalgama- 
t'on  of  filver  ore  is  that  of  Alonzo  Barb*.  He  divides 
the  ores  into  two  claifes  :  I.  thofe  which  are  bed  treat 
ed  by  fiie  and  fufion  ;  and,  2.  fuch  as  are  moft  fit  for 
amalgamation.  Thofe  called pacos  and  tacana,  may  be 
amalgamated  ;  but  that  none  of  their  richer  contents 
may  be  loft,  it  will  be  bed  to  combine  them  with  lead, 
and  proceed  by  cupellaticn.  The  former  of  thefe  ores 
has  no  luftre  or  brightnefs.  It  is  faid  to  be  of  a  reddifh 
yellow,  foft  and  friable  ;  feldom  rich  in  filver,  and 
moftly  valuable  on  account  of  its  being  eafily  got  from 
the  mine.  Tacana  is  a  rich  filver  ore,  of  a  black  co 
lour,  fometimes  of  a  grey  or  of  an  afh-colour;  or  a 
brown,  rich,  filvery  earth.  3.  TheJ&wo  is  too  rich 
for  pulverifation  and  amalgamation,  and  is  therefore 
fimply  melted  down  with  the  tacana.  This  feems  to 
be  the  fame  with  the  horn-filver  ore  ;  and  is  defcribed 
as  almoft  entirely  confiding  of  native  filver,  .of  a  black, 
grey,  of  greenifh-white  colour.  Barba  fays  that  they 
found  at  Potofi  fome  plomo  of  a  cinnabar  colour,  which 
they  had  not  feen  any  where  elfe  ;  but  Baron  Born 
thinks  that  here  he  has  miftaken  the  red  filver  ore  for 
another  fpecies.  Ffezier  aflerts,  that  in  what  he  calls 
the  plomo  ronco^  the  native  fiiver  appears  upon  rubbing 
orfcratching  it,  and  that  it  gives  vhite  and  very  pure 
filverby  fimple  fufion  without  any  amalgamation.  In 
the  imperial  cabinet  at  Vienna,  there  is  a  fpecimen 
weighing  about  a  pound,  of  black  hern  filver  ore  from 
Potofi,  en  the  po;iilied  fur-face  of  which  the  virgin 
filver  appears  very  plainly.  4.  The  maclacado  (virgin 
iilver  or  gold  grown  in  the  matrix  in  the  form  of  wire 
or  hair),  is  amalgamated  in  the  mortar.  5.  Theforo- 
ehes  (lead  ores  containing  filver),  are  melted  along 
with  the  rofichr  and  conclifo,  two  kinds  of  red  filver 
ore,  6.  The  negrlllos  (grey  copper  and  white  filver 
' I  i  2  ores) 


L"    386    3 

I-LV.O)  may  be  refined  by  amalgamation,  though  they 
are  mere  tit  for  fire.  , 

Belides  this  cUifnflcation  in  ftich  as  are  fit  for  fire, 
and  thofc  for  amalgamation,  the  ores  require  further 
to  be  ibited  into  inch  as  require  the  addition  of  par- 
ticulur  iubftances  for  their  amalgamation.  Vitriol  is 
generally  -hurtful,,  efpecially  when  fait  is  added  to  the 
vitriolic  rj'-js ;  and  it  requires  the  addition  of  iron, 
tin,  lead,  and  lime,  in  order  to  counteract  its  effects  ; 
tut  in  ii.iae  caks  k  is  of  fervice,  and  promotes  amril- 
f>;arnation.  The  calcination  of  vitriolic  ores  is  of  no 
ierv:ee,  but  rather  the  contrary,  as  it  difengages  tlie 
vitriol,  and  brings  on  a  vitriolic  efilorefcence.  It  may, 
however,  be  feparated  by  wafliing  till  the  water  comes 
off  liiftelels  and  fweet.  The  amalgamation  Is  difturb- 
f.il  by  fill  pint  r,  bitumen,  and  antimony,  only  by  the 
irnoi  thnefs  and  needle-like  figure  of  the  particles, 
which  reduce  the  quickfilver  to  a  kind  of  duft.  The 
ores  mixed  with  tliefe  always  run  into  reguli,  and  mud 
therefore  be  put  into  a  ilrong  calcining  fire  ;  if  melted 
without  calcination,  they  would  rim  entirely  into  drofs 
-and  fcoria. 

The  finer  the  ores  are  pounded  Co  much  the  better ; 
and  after  putting  the  powder  thro'  a  fine  fieve,  the  coar- 
ier  part  goes  again  to  the  mill :  they  ought  to  be  pre- 
viouily  burnt,  in  order  to  affift  the  operation  of  grind-* 
ing.  The  beft  method  of  obtaining  fine  powder  is  by 
warning  over  ;  but  as  this  is  very  apt  to  pack  and  turn 
clammy,  it  ought  to  be  mixed  with  fand. 

The  ores  are  known  to  be  fufficiently  calcined  by 
their  change  of  colour  and  lofs  of  brightnefs.  Barbii 
tells  us,  that  all  bright  ores  mull  be  calcined,  but  with 
great  care,  that  no  vitriol  may  be  difengaged,  as  that 
proves  injurious  to  the  amalgamation  ;  but  baron  Born 
lays,  that  one  of  the  greateit  objects  in  the  calcination 
of  the  Hungarian  ores  is  to  decompole  the  fulphur  into 
vitriol,  as  promoting  the  decomposition  of  the  fait, 
The  amalgamation,  is  like  wife  promoted  by  burning 


[     3*7     3 

and  calcination,  in  as  far  as  it  promotes  the  pulveri 
zation  of  the  ore,  a;  d  affifts  the  action  of  the  quick- 
filver  ;  but  it  is  chietiy  ufeful  in  the  black  and  grey 
filver  fire-:.  It  can  only  be  determined  by  circuwiitan- 
ces  whether  it  be  better  to  pulverize  the  ores  before 
or  afu-r  calcination.  Their  value  is  bei't  known  by 
pounding  them  previous  to  calcinati<  n.  The  ftufFmuit 
be  conftantly  ithred  during  the  time  it  is  calcining,  and 
fome  powder  taken  irom  the  n.afs  to  be  tried  with 
qulcklilver  and  fu;t.  The  thickening  of  the  quick- 
iilver,  and  the  gram  of  the  iluff,  jfhowwhat  additions 
are  r.ecefiary,  or  whether  calcination  be  completed 
or  not.  When  ores  are  calcined  i'i  lumps,  the  fire  does 
not  act  eqa.il!)  up  n  all  their  pms;  though  this  me 
thod  is  attended  with  the  advantage  of  lofing  much 
lefs  dull,  as  well  as  faving  the  expcnce  of  (tamps  and 
mills. 

Ores  cannot  be  calcined  in  reverberatory  furnaces, 
as  the  heat  would  run  it  together,  and  part  of  t»ie 
metals  themfelves  would  be  carried  off  by  the  ftrong 
current  of  air  and  the  violent  fmoke.  Barba  recom 
mends  a  furnace  of  an  oblong  fquare  figure,  with  three 
vaults  over  each  other;  the  fire  is  put  in  the  lower- 
mo  ft,  and  the  ore  into  the  two  upper  ones.  The  heat 
circulates  by  means  of  lateral  openings  in  the  walls, 
and  is  let  out  on  the  back  without  a  flue.  The  heat  is 
graduated  by  registers  and  dampers  on  the  outfide. — 
Whatever  kind  of  furnace,  however,  is  ufed,  fome  of 
the  ore  \vi  1  have  clotted,  and  muft  therefore  be  ground 
to  a  fine  powder;  but  to  prevent  as  much  as  poflible 
thefe  inconveniences,  the  hard  ores  ought  to  be  cal 
cined  before  they  go  to  the  mill,  and  the  foft  ones  af 
ter,  but  with  proper  additions.  Tne  irony  ores,  which 
re  lift  fhe  fire  longer,  are  calcined  with  an  addition  of 
fulphur,  or  of  fulphureous  and  antimonial  matter  pro 
portioned  to  the  iron  they  contain  ;  but  fulphureous 
and  antimonial  ores  require  to  be  calcined  with  the 
fcoi  ia  of  iron.  Arfenical  ores,  or  thofe  mixed  with 
I  i  3  orpiment 


C    388    j 

OrpinVent  and  fandarac,  are  calcined  with  lead  glance  ; 
afcd  tkofc  mixed  with  white  or  black  bitumen  muit  be 
calcined  with  in  n  fcoria  or  pounded  limeftone. 

The  impurities  of  ores,  and  the  additions  proper  to 
be  made  to  them,  are  determined  by  pounding  them 
coarfely,  and  throwing  them  upon  a  heated  plate  of 
iron.  If  t.he  fmoke  be  white  or  black,  it  mows  a  mix 
ture  of  bitumen  of  thefe  colours  ;  if  yellow,  it  {"hows 
crpiment ;  if  red,  fandarac ;  if  greeniih  yellow,  ful- 
phur. 

Salt  ought  net  to  be  ufed  in  the  calcination  of  ores 
as  it  would  calcine  the  filver;  and  the  duration  of  the 
calcining  muit  be  determined  by  the  change  of  colour 
which  the  ores  undergo  by  calcination  by  themielve^, 
;did  the  brightnefs  they  afilime  by  trituration  with 
quickfilver.  It  is  alib  a  mark  of  fufficient  calcination 
when  ar-itimonial  and  fulphnreous  ores  no  longer  fend 
out  a  difagreeable  fmoke  ;  if  the  thick  and  black  fmoke 
of  bituminous  ores  become  white  ;  and  if  the  filver  in 
the  ft  a  if  appears  in  white  glittering  fparks.  Vitriolic 
ores  may  alfo  be  calcined  in  the  fame  manner ;  but  they 
require  a  longer  time  with  the  addition  of  alum  and 
fait:  they,  however,  require  no  farther  addition  in 
the  fubfequent  operations  ;  and  in  the  courfe  of  four 
days  all  their  filver  will  be  taken  up  by  the  quickfilver. 
l^efs  quickfilver  will  alfo  be  loft  ;  for  as  there  is  no  ccca- 
iion  for  the  frequent  turning  and  working  of  the  heap, 
a  very  fmall  part  of  it  only  can  be  turned  into  ufcleis 
duft.  Vitriolic  ores  ought  always  to  be  well  waftied 
with  water  before  they  are  calcined  ;  and  if  there  is 
ftill  a  fufpicion  of  their  being  vitriolic,  they  muft  be 
tr  e  J  by  quickfilver  :  if  it  takes  a  lead-colour,  the  ftuft 
muft  be  \vaflied  till  iron  put  into  it  no  longer  takes  a 
copper  colour.  The  lixivium  is  kept  as  an  uieful  ad 
dition  to  fome  ores. 

Amalgamation,  according  to  Alonfo  Burba's  me 
thod,  is  performed  in  three  ways,  viz.  in  heaps  or 
caxons,  in  the  boiler,  and  in  mortars. 

1-.   In 


[     3*9     3 

1.  In  heaps.  Before  the  operation  takes  place  in 
the  large  XT  ay,  an  eflay  is  made  of  three  or  four  pounds 
of  the  fine  fifted  powder  taken  from  the  general  quan 
tity  ;  and  according  to  the  produce  of  this  he  calcu 
lates  that  of  the  whole.  He  tries  it  alfo  with  quick- 
filver,  tti  know  perfectly  the  method  he  is  to  follow, 
and  the  additions  that  are  to  be  made.  In  this  ei- 
fay  the  following  method  is  adopted:  I.  The  mat 
ter  is  elix--vted,  to  extract  the  vitriol  if  there  be  any. 
2.  One  pound  of  the  lixiviated  matter  is  tried  with 
quick filvcr  and  fait,  carefully  obferving  the  colour  and 
ks  change.  If  ihe  quickfilver  a  Humes  the  appearance 
of  illver  filings,  and  thefe  quickfilver  flakes  become 
thinner  and  thinner,  it  proves  that  the  amalgamation 
goes  on  fuccefsfully,  and  that  the<e  is  no  occafion  for 
any  addition.  The  whole  is  ilirred  from  time  to  time, 
till  the  qaickfilver  feems  to  diminifh,  and  recover  its 
natural  form,  but  without  dividing  into  fmall  globules; 
after  which  fee  matter  is  to  be  waihed,  as  all  the  iilver 
is  by  that  time  complete!}  taken  up.  The  ores  of 
Verer.guela  de  Pacages  are  treated  only  with  quickfilver 
and  fait,  and  yield  their  full  produce. 

When  the  ore  turns  black,  iron  is  added  ;  when  of 
a  light  lead-colour,  tin  ;  if  a  dark  lead-colour,  lead  ; 
and  if  of  a  y^liowith  or  gold  colour,  lime.  The  three 
firft  of  thefe  are  ftyled,  by  Baron  Born,  "  very  idle 
and  ufelefs  additions." — The  ore  frequently  divides 
into  fmall  and  powdery  globules,  in  confequence  of 
the  hardnefs  of  the  minerals,  or  from  too  much  ftir- 
r'ng  ;  but  this  may  be  prevented  by  calcination  before 
it  is  reduced  to  powder,  or  by  lefs  ilirrinsr.  In  a  great 
many  operations,  however,  this  quickfilver  dull  can 
fcarcely  be  avoided.  It  ferves  the  workmen  as  an  in 
dex  of  the  progrefs  they  have  made,  or  fometimes  as 
a  direction  how  to  operate ;  and  has  different  names 
according  to  the  caufe  by  which  it  is  produced  ;  as 
quickfilver  duft,  the  dud  of  addition,  and  filver  duft. 
The  firft  of  thefe  arifes  fimply  from  too  great  divifion, 


[     390     ] 

and  is  white  without  any  quicknefs,  frarcely  moving 
when  the  master  is  itirred  with  warer  ;  it  frrks  fome- 
what  to  the  bottom,  and  runs  into  gl  -hales  when  bro 
ken  between  the  fingers.  .The  lecoud  is  produced  by 
the  amalgam  uf  lead  and  tin;  and,  vv^en  prefled  be 
tween  the  fingers,  unites  wi'b  the  q-uickiilver  which 
had  bcgu.i  to  combine  with  the  filver.  The  third 
ir-.«m  the  amalgam  of  filver  :  it  finks  toward 
the  coarser  fluff  0:1  the  bottom,  nd  floats  about  in 
fi .'. <  -s  of  different  uzes  ;  turwi.  ;<r  ii'.to  an  amalgam  when 
rubbed  or  prelTed  between  the  lingers.  Ail  of  thefe 
are  produced  chiefly  when  there  are  lead,  marcaf'te, 
and  iiony  ores  in  the  mixture  ;  or  by  vitriol  of  copper,  < 
which  i^  particularly  productive  of  this  minute  divilion 
of  the  quicklilver.  They  are  produced  a-fo  by  too 
plentiful  an  ad.Mi'inn  of  fait,  which  thickens  the  water 
an  I  prevents  the  ddfcent  of  the  particles  of  quick- 
filver. 

According  to  the  produce  of  the  effa-y  the  large 
heap  is  regulated.  It  is  fit  ft  wetted  with  water,  and 
mixed  with  ;t  due  proportion  of  fait  ;  but  at  the  be 
ginning  only  one  third  of  the  quickiilver  and  one  half 
of  the  lead  and  tin  are  added.  It  is  tinned  over  once 
every  day  during  the  two  fiill:  days,  becaufe  the  quick- 
filver  being  then  uncombincd  wou-d  be  apt  to  be 
driven  off  iu  fmall  globules,  and  a  great  wa'le  occa- 
fioned.  The  heap  is  IrkewHe  too  much  cooled  by  the 
addition  of  too  much  qinckfilver  at  once  ;  fo  that  it  is 
better  to  put  it  gradually  to  the  other  matters.  The 
lead  and  tin  are  always  thrown  into  the  heap  along 
wMi  the  quickfilver  ;  but  too  much  of  either  is  hurt 
ful,  by  deadening  the  quickiilver,  and  preventing  the 
amalgamation.  All  thefe  additions,  however,  muft  vary 
according  to  circumltances  ;  obferving  that  the  quanti 
ties  added  muft  alwayc  be  lefs  and  lefs  in  proportion  as 
the  amu!;<am  advances  to  perfection.  The  matter 
fhould  be  !;ept  rather  dry  than  otherwife,  and  two, 
parts  of  amalgam  be  in  the  heap  to  one  of  fluid  qmck- 

iilvex 


I     591  ,  3 

fi!ver.  Too  great  an  abundance  of  this  fluid  mafs  is 
very  detrimental,  en  account  of  the  quantity  of  quick- 
filver  duft  which  it  occafions  ;  and  if  the  other  ingre 
dients  are  accidentally  wafted,  the  duft  of  addition  will 
be  changed  into  qu'idfiher  duft  ;  which  having  very 
little  weight,  will  be  poured  off  along  with  the  water. 
But  when  lime  is  added,  the  whole  mult  be  mixed  at 
(nice,  and  the  entire  heap  turned  over  two  or  three 
Jays,  till  the  quickfilver  be  added.  Too  much  lime 
prevents  the  union  cf  the  two  metals,  and  is  an  incon 
venience  which  cannot  be  remedied. 

The  heaps  are  frequently  turned  and  worked  over 
after  the  firit  two  days,  which  is  attended  with  feve- 
ral  advantages  ;  as  that  the  quickfilver  is  thus  heated  ; 
more  thoroughly  mixed  with  the  matter,  and  the  fil- 
ver  is  purified  by  the  frequent  rubbing.  The  heaps, 
however,  are  fubject  to  various  accidents,  owing  to 
the  difference  between  the  various  kinds  of  ores,  which 
cannot  always  be  exactly  known.  When  the  quick 
filver  is  deadened  by  too  large  an  addition  of  lead, 
iron,  tin,  or  lime,  it  lofes  its  oval  form,  and  aifumes 
a  vermicular  one  :  if  iliaken  in  a  glafs,  or  Other  vcifv1, 
without  water,  it  adheres  to  the  fides  in  threads,  and 
is  unfit  for  taking  up  the  filver.  The  beft  remedy  is 
vitriol  of  copper,  or  the  lixivium  of  vitriolic  ores  al 
ready  mentioned  ;  or  powder  of  copper  may  be  thrown 
into  the  heap.  All  additions  of  this  kind,  however, 
mud  be  made  very  cautioufiy,  and  in  confluence  of 
experiments  made  by  fmall  effays,  which  determine 
the  quantity  of  materials  to  be  ufed.  When  the  heaps 
have  too  much  vitriol,  without  any  correcting  ingre 
dient,  the  quickfilver  has  a  leaden  colour,  and  the 
fmaller  particles  aflume  a  fpherical  form.  Iron  might 
be  added  to  abibrb  the  too  great  quantity  of  vitriolic 
acid  ;  but  thei  e  is  no,  certain  rule  for  the  proportion 
to  be  added,  fo  that  it  mult  be  determined  by  experi 
ment, 

When 


[     392     ] 

When  the  quickfilver  apipears,  on  turning, the  heaps 
like  a  bunch  of  grapes,  this  Ihows  an  excefs  of  fait, 
which  prevents  the  quickfilver  from  combining  with 
the'filver  :  it  is  to  be  remedied  by  the  addition  of  ibme 
coarfe  fluff  which  clsanfes  the  fluid.  Some  add  allies  : 
but  the  beft  and  nioft  natural  remedy  is  alum,  which 
is  found  at  Potofi  in  abundance,  and  whitens  the  fil- 
ver.  If  the  heap  be  no:  turned  equally,  or  the  quick- 
rllver  added  at  a  proper  time,  or  if  the  filver  do  not 
unite  with  it,  fome  of  the  filver  will  appear  in  a  dry 
form  and  lie  on  the  coarfer  fluff  like  a  cobweb  ;  and 
if  not  fkimmed  off  in  time  will  be  carried  away  by  the 
wafhmg  water.  To  collect  this  dry  fiiver,  and  the 
fineft  quickfilver  duft,  fome  filver  amalgama  is  preffed 
upon  it  through  a  chamois  fkin  ;  arid  the  whole  is 
,once  more  turned  and  worked  over.  The  frequent 
turning,  the  heat  of  the  climate  and  feafon,  as  well  as 
the  fermentation  produced  in  the  heap  by  the  vitriol 
and  other  additions,  all  promote  the  amalgamation  ; 
but  cold,  neglect  of  ftirring,  and  the  quickfilver  aflum- 
ing  a  lead  colour,  are  againft  it.  It  is,  however,  very 
difficult  to  determine  the  maturity  of  the  heap,  when 
all  the  filver  is  taken  up,  and  the  matter  m.iy  go  to 
the  wafhmg  ;  though  great  inconveniences  attend  an 
ignorance  in  this  refpect.  If  wafhed  too  fo~>n,  fome 
iilver  is  left  in  the  leavings:  and  if  worked  too  1  >ng 
there  is  a  lofs  of  quickfilver  as  well  as  time  and  la- 
b.mi.  The  difficulties  attending  the  knowledge  of 
this  important  point,  are  by  our  author  enumerated 
as  f 'How  ;  "  The  heap  may  appear  not  to  requ're  any 
additional  quickfilver  ;  the  filver  daft  may  appear  to 
be  completely  coPefted  ;  that  of  quickfilver  may  be 
gin  to  make  its  appearance :  the  amaljr.MiKi  may  be 
gin  to  appear  pure,  and  to  fhow  a  gold  colour:  and 
yet  filver  may  remain  in  the  leavings.  The  in  oft  in 
fallible  teft  of  the  maturity  of  the  heap,  is  the  eifay 
of  the  triturated  ftuff  by  fire.  If  no  filver  is  produced 
thereby,  then  fo  much  quickfilver  is  thrown  into  the 

heap, 


[     393     ] 

heap,  that  it  may  contain  three  parts  of  amalgama  to 
two  of  filver,  or  at  Icaft  one  part  of  quicklilvcr  to 
two  of  amalg.tma.  By  this  additional  frefh  quick- 
filver,  all  'he  d  .ft  of  quickiilver,  ard  the  dry  and  un- 
combined  quickiilver,  are  perfectly  collected  the  amal 
gama  is  the  heavjer  for  it,  and  finks  the  more  readily 
to  the  bottom  when  brought  to  the  Waihing-tiibi — 
Some  clean  quickfilver  is  alfo  put  into  the  bottom  of 
this  tub:  the  infide  of  which  muft  be  lir-pd  with  iron 
plate  well  cleaned,  and  rubbed  with  quickiilver;" 
(though  the  laft  operation  feems  to  be  quite  fuperflu- 
ous,  as  mercury  \vill  not  in  the  leaft  unite  with  iron 
by  rubbing.)  "  The  fluff  brought  into  the  tub 
muft  be  diluted  with  a  great  quantity  of  water,  and 
be  ftirred  round  with  a  peftle  lined  with  iron-plate  in 
fuch  a  manner  that  it  may  turn  round  fix  times  one 
way  and  fix  times  the  other,  always  touching  the  bot 
tom  ;  the  unconnected  bodies  of  quickfilver  and  amal 
gam  are  thereby  to  meet,  to  combine,  and  to  fall  to 
the  bottom.  To  recover  the  fait  which  had  been  mix 
ed  with  the  heap,  the  water  muft  be  evaporated  :" 
but  the  Baron  t'bferves,  that  at  Shemnitz  no  fait  is 
recoverable  from  the  lixiviam  ;  and  if  any  be  recover 
ed  by  the  Spaniards,  it  only  ihows  that  they  add  too 
much,  and  that  part  of  the  remainder  is  undecompo- 
fed  by  the  vitriolic  acid.  The  quickfilver  is  feparated 
from  the  amalgama  much  in  the  fame  way  as  already 
defcribed. 

2,* Amalgamation  ly  boiling,  \vas  accidentally  difco- 
vered  by  Barba,  in  an  attempt  to  fix  qiuckfilvfer. — 
On  mixing  filver  ore  finely  powdered  with  quickfil- 
ver,  and  boiling  it  with  water  in  a  copper  veifel,  he 
found  that  the  metals  readily  united  ;  and  thus  having 
difcovered  afhorrermethod  of  amalgamation,  he  gradu 
ally  improved  and  introduced  it  into  practice  in  Peru. 
In  this  operation  the  boilers  muft  be  of  copper,  ear 
then  or  other  vefiels  being  found  not  to  anfwer :  the 
copper  alfo  muft  be  pure,  becaufe  the  quickfilver  would 

dilTolve 


[     394     J 

diflblve  the  metals  with  which  it  is  alloyed.  TSey 
muft  be  in  the  fhape  of  inverted  cones  and  flat-bot 
tomed.  The  under  part  has  a  rim  of  fix  or  eight 
inches  high  and  half  an  inch  broad,  all  beat  of  one 
piece.  Other  copper  plates  are  fixed  in  the  infide  with 
copper  nails  ;  and  care  muft  be  taken  that  it  be  water 
tight;  that  no  quickfilver  may  run  off;  and  for  the  bet 
ter  fecurity,  the  infide  of  the  boiler  may  be  lined  with 
lime  and  ox-blood.  The  boilers  may  be  of  any  mag 
nitude  ;  their  upper  parts  being  furrounded  with  iron 
rings  with  ftrong  handles,  into  which  a  crofs  Aboard  is 
wedged.  In  the  middle  of  this  board  is  a  hole  for  the 
ipindle  to  move  in.  The  fpindle  is  of  light  wood, 
and  moves  on  a  brafs  pivot  in  the  bottom.  It  has 
four  wooden  wings,  with  three  or  four  perpendicular 
bars  alfo  of  wood  ;  the  fartheft  from  the  fpindle  being 
the  (liorteft  ;  the  nighefl  fo  long  as  to  fweep  the  bot 
tom.  It  is  turned  by  a  moveable  handle  on  the  up 
per  end. 

Thefe  boilers  are  put  into  an  *>blong  furnace,  ca 
pable  of  holding  10  of  them  ;  the  fire-place  being  in 
the  middle,  and  the  flame  and  fmoke  pafling  under  the 
boilers,  and  going  out  at  both  ends  of  the  furnace  by 
two  chimnies.  The  fire  being  lighted,  firft  the  wa 
ter,  then  the  fine  fluff,  and  at  laft  the  quickfilver,  is 
put  in  ;  obferving  always  that  the  bottom  be  fully  co 
vered  with  quickfilver.  The  water  muft  always  be 
kept  boiling,  otherwife  the  operation  may  be  inter 
rupted  or  become  tedious  :  on  account  of  the  evapo 
ration,  the  boilers  mult  be  fupplied  with  a  quantity  of 
water,  in  fmall  quantities  at  a  time,  that  the  boiling 
be  not  checked.  The  fluff  muil  be  proportioned  to 
the  fize  cf  the  boiler:  if  too  little  be  put  in,  the. amal 
gamation  goes  on  too  (lowly  ;  while  too  much  would 
not  allow  the  mafs  to  be  thick  enough,  or  to  boil  with 
iufficient  freedom.  Some  of  the  amalgam  is  to  be  ta 
ken  out  from  time  to  time  with  a  long  ladle,  and  the 
progrefs  of  the  operation  is  judged  of  by-the  colour. 
4  The 


C     395     3 

The  etfay  of  the  fluff  determines  whether  all  "the  m*. 
ver  be  taken  out  of  it  in  this  manner.  Some  quick- 
diver  is  then  thrown  upon  the  furface  of  a  fample  of- 
the  boiled  fluff,  and  worked  round  with  it  in  a  velfel- 
two  or  three  times.  If  the  quickfilver  rifes  and  takes 
up  fome  of  the  fluff,  fome  filver  remains ;  if  not  the 
whole  is  taken  up.  Then  the  fire  is  flopped,  the 
fpindle  is  taken  out,  and  the  water  and  fluff  let  oft". 
The  coarfer  matter  on  the  quickfilver  may  at  all  events 
be  wafli-ed  in  cold  water,  and  go  once  more  to  the 
mill.  Almofl  the  whole  of  the  fllver  amalgama  lies 
upon  the  fur  face  of  the  quickfilver,  immediately  under 
the  (luff,  fometimes  four  or  five  fingers  thick  ^  the  fire 
under  the  boilers  preventing  the  filver  from  uniting 
with  the  quickfilver  in  the  bottom.  This  metal,  when 
poured  off,  muft  be  preiled  and  treated  in  the  uiu;il 
manner. 

The  advantages  attending  this  method  are,  that  the 
heat  promotes  the  union  of  the  metals,  while  the  boil 
ing  of  the  water  and  ft  wring  of  the  mixture  with  the 
fpindle  bring  them  more  frequently  in  cental  with 
each  other  in  a  quarter  of  an  hour,  than  they  would 
be  in  feveral  days  in  the  common  method  ;  by  which 
means  the  whole  procefs  is  finifhed  in  about  24  hours* 
Lefs  quickfiiver  is  alfo  loft  by  it ;  for  being  always  co* 
vered  with  water,  it  cannot  evaporate ;  and  in  well 
managed  and  fuccefsful  operations,  no  quickfilver  dufl 
is  produced:  but  the  greatefl recommendation  is,  that 
it  is  not  attended  with  any  lofs  of  filver,  fo  that  even 
the  pooreft  ores  will  yield  all  that  they  contain.  Bar- 
ba  looks  upon  the  profit  of  this  method  above  the 
other  to  amount  to  25  dollars  for  every  heap  of  50 
quintals  :  even  making  allowance  for  the  coals.  The 
only  objections  are,  that  both  filver  and  copper  are 
apt  to  be  loft  by  the  corrofion  of  the  copper-boilers : 
but  if  the  copper  be  pure,  there  is  no  great  reafon  to 
be  apprehenfive  of  any  thing  of  this  kind ;  or,  at  all 
events,  the  bottom  of  the  boiler,  which  is  conftantly 
K  k  expofed 


C    596    ] 

to  the  aftion  of  the  quickfilver,  may  be  fecii- 
red  by  a  copper  ring  three  or  four  inches  high  ;  and 
the  bottom  itlelf  may  be  fecured  in  the  fame  manner  ; 
fo  that  when  corroded  they  may  be  changed  for  new 
ones :  or  the  boilers  may  be  paved  or  lined  with  var- 
riilhes  or  mortars  of  different  kinds  ;  which  will  as  ef 
fectually  prevent  any  lofs.  While  the  whole  is  boil 
ing,  the  quickfilver  violently  feizes  on  the  other  me 
tal  ;  by  which  means  the  amalgam  is  filled  with  many 
heterogeneous  particles.  Thefeare  feparated  by  walh- 
ing  in  quickfilver,  on  the  furface  of  which  they  fwim 
like  fcoria,  and  may  eafily  be  taken  off,  till  the 
quickfilver  flic-ws  its  ufual  brightnefs  ;  and  as  this  can 
not  be  done  without  taking  off  fom-2  of  the  metals 
alfo,  thefcum  may  be  referved  for  the  next  operation. 
The  advantage  of  amalgamation  by  boiling  chiefly 
appears  in  this,  that  heaps,  in  which  by  too  large 
additions,  the  quickfilver  has  been  totally  diffolved  fo 
as  to  difappear,  may  be  eafily  cured  by  boiling  them, 
in  iron  or  copper  veflels  wTith  bits  of  iron  ;  for  chen 
the  quickfilver  appears  again  in  its  proper  metallic 
form  and  brightnefs. 

3.  Amalgamation  in  mortars.  It  is  difficult  to  pro 
cure  the  full  produce  from  ores  which  contain  native 
gold  and  filver  either  in  the  form  of  hair  or  wire,  or 
in  larger  lumps  and  nodules.  Thefe  cannot  be  com 
pletely  pounded,  nor  can  they  be  amalgamated  ;  for  the 
mercury  will  not  diffolve  the  large  particles  of  gold 
and  filver  ;  and  when  they  are  treated  by  fire,  the  ftub- 
borr  nature  of  their  matrices  occailons  a  great  lofs  of 
metal.  The  following  method  of  treating  them  in  a 
mortar  was  discovered  by  a  Francifcan  friar. 

A  r."imd  conical  hole  is  cut  in  a  hard  ftone,  half 
in  diameter  at  top,  of  an  equal  depth,  and  (lope- 
ing  into  a  truncated,  or  rather  obtufe  and  nearly  flat 
bottom,  of  about  four  inches  in  diameter.  Some 
quickfilver  is  poured  5n*o  it,  together  with  a  propor 
tional  quantity  of  fmall  bits  of  the  native  metal  or  ore  ; 

after 


C     397     ] 

after  which  they  are  triturated  with  an  iron  peftle. 
By  this  violent  trituration,  the  gold  and  filver  combine 
with  the  quickfilver  ;  and  the  finer,  lighter  fluff  of  red 
filver  ore  and  other  filver  calces,  which  are  generally 
found  with  native  filver,  runs  ofF  by  means  of  afmall 
launder  and  current  of  water.  It  is  not,  however, 
fuffered  to  run  away,  but  is  left  to  fettle  for  common 
amalgamation. 

Mortars  of  the  dimenfioris  above  defcribed  being' 
too  fmall  for  any  coniiderable  quantity  of  ore,  Barba 
propofes  to  fubftitute  in  their  place  larger  fton.es  of  a 
concave  figure,  with  vertical  grinders,  as  in  oil-mills  ; 
or  common  horizontal  and  parallel  grinders  of  the  grill- 
mill.  The  ore  and  quickfilver  are  put  between  thefe 
ftones,  with  a  fmall  ftream  of  water  ;  which,  running 
off,  will  carry  away  the  lighter  ftuff,  whi'lft  the  gold 
and  filver  will  remain  at  the  bottom,  taken  up  by  the 
quickfilver. 

There  are  feveral  other  methods  of  amalgamation 
defcribed  in  Baron  Born's  work,  as  praclifed  by  the 
Spaniards  of  South  America  :  but  as  all  of  them  agree 
in  the  mod  material  circumstances  with  thofe  already 
mentioned,  we  ih all  only  farther  take  notice  of  that 
invented  by  the  Baron  himfelf,  and  by  him  lately  in 
troduced  at  Shemnitz  in  Lower  Hungary. 

This  method  is  very  pompuoufly  related,  and  at 
great  length,  in  his  work  on  the  fubjeft.  His  theory 
contains  the  following  particulars  : 

1.  Quickfilver  has  a  tendency  to  unite  with  other 
metals  and  femi metals,  and  to  quicken  or  animate  them 
according  to  certain  laws  of  affinity  which  are  deter 
mined  by  expeiience. 

2.  It  unites  with  gold,  filver,  copper,  tin,  lead,  bif- 
muth,  and  zinc,  without  heat ;  but  with  other  metals 
and  femimetah  it  will  not  unite  but  in  a  Hate  of  fuiion. 
It  unites  with  tin  and  bifmuth  moie  eafuy  than  with 
gold  and  iilver ;  and  with  thefe  more  readily  than  with 
copper. 

K  k  2  3  The 


j.  The  vmS'pn  of  qukklllver  with  other  metals  is  pro 
moted  by  heat. 

4.  This  u.F;5on.ij>  alfo  greatly  promoted  by  mechani 
cal  comminution. 

5.  No  amalgamation,  or  only  a  very  flow  and  partial 
one   will  take  place,  if  the  fui face  of  the  quickfilver 
<sr  me  tail  ic  particles  be  covered   with  a  coat  of  hete 
rogeneous  matter  ;  which  happens  chiefly  in  the  amal 
gamation  of  ores  where  the  fine  particles  of  the  metal 
are  involved  in  fulphur  and  arfcnic. 

.  •  6.  Hence  it  is  necefiary  to  free  the  noble  metals 
from  the  &cny  matter  which  furrotinds  them,  and  to 
reduce  the  bafer  ones  from  their  calciform  to  a  me 
tallic  Rate,  before  they  can  be  amalgamated  with  fuc- 
. 

7.  Particles  of  gold  and  filver  may  be  freed  from  the 
fior.y  mattcrjs  which  involve  them  by  trituration;   and 
irom  fulphur  and  arfenic,  by  calcination. 

8.  In  calcination,  feme  part  of  the  fulphur  is  de- 
itroyed,  and  vitriolic  acid  difeagaged  ;  which,  combi 
ning  with. the  earthy  nratters  contained  in  the  ore,  as 
well  as  the  calces  of  the  bafer  metals  mixed  with  it, 
iiill  leave  the  gold  and  filver  involved:  whence  it  is 
ncceflary  to  employ  fueh  chemical  agents  as  will  free^ 
the  particles  of  thele  metals  irotri  their  heterogeneous 
coat,  and  keep  their  furface  as  well  as  that  of  the 
quickfilver  clean,  without  acling  either  upon  the  gold 
-or  filver.     Thefe  agents  are  principally   the  mineral 
acids,  which  act  varioufiy  according  to  their  different 
Features.     The  marine  acid  is  mod  efficacious  for  gold. 

.or  filver  ores;  but  it  would  be  exceedingly  expenfive 
to  ufe  it  in  its  proper  form,  fo  tjiat  it  is  neceilary  to 
take  fome  method  of  expelling  it  extemporaneou^y 
irom  common  fait  by  means  of  oil  of  vitriol. 

9.  The    calcined   ore,    when    pulverifed,    rnufl  be 
.wetted  with  water,  for  the  purpofe  of  diilclving  ih<; 
difengaged  vitriolic  acid  and  the  earthy  and  m.etallic 

'  Tfalts,  which  are  produced  by  it  in  proportion 


C     399     I 

to  the  fulplmr  contained  in  the  ore.  Vitriol  is  pro 
duced  by  calcination  only  in  this  proportion  ;  and 
hence  if  the  ore  does  not  naturally  contain  a  fuffici- 
ency  of  fulphur  to  produce  vitriol  for  the  purpcfe  of 
decompofition,  it  will  be  neceflary  to  add  fom -thing 
cf  this  kind.  Vitriol  of  copper  or  of  iron  will  an- 
fwer,  but  the  former  is  preferable.  If,  therefore,  the 
pulverifed  ore,  which  has  once  gone  through  the  pro- 
cefs  of  amalgamation,  fhould  (till  appear  to  contain 
gold  or  fiivcr,  mix  it  with  fome  additional  vitriol  and 
common  ialt ;  leave  it  for  fome  time  to  macerate  by 
itfelf ;  asd,  at  a  fecond  trituration  with  quickfilver,  a 
coniiderable  quantity  of  filver  will  be  found  in  the 
amalgama  which  had  not  been  extracted  in  the  firil, 
though  common  fait  had  been  ufed  in  it.  Thus  the 
common  fait  may  be  decompofed  in  the  wet  way. 

10.  To  decompofe  the  common  fait  in  the  dry  way, 
the  ore  muft  be  properly  (lamped  and  lifted,  and  the 
mixtures  made  up  with  a  proporti-  nal  quantity  of 
pnlverifed  common  or  reck  fait,  and  then  undergo  an 
adequate  calcination  in  an  open  fire.  Thus  the  com 
mon  fait  will  be  decompofed  according  to  the  nature 
of  the  mixture  ;  either  by  the  vitriolic  acid  produced 
by  the  decompofition  of  the  fulphur,  or  otherwife.— 
The  muriatic  acid,  thus  difengaged,  diffolves  the  he 
terogeneous  particles  in  wluch  the  metals  are  involved, 
and  allows  the  quickfilver  to  act  npon  them  much  more 
effectually  than  it  could  have  been  enabled  to  do  by 
any  mechanical  comminution ;  and  this  the  more 
fo  as  it  takes  up  even  thofe  particles  of  dephlogiftica- 
ted  iron  upon  which  the  other  acids  arc  incapable, 
of  acVirg.. 

u.  The  calcination  and  corrofion  of  the  bafer  me 
tals  is  indifpenfably  necelTary,  efpecially  in  a  natural 
combination  of  gold  and  copper  ;  for  the  affinity  of 
thefe  two  is  fo  ftrong,  that  unlefs  the  lat.er  be  per- 
feftly  calcined,  or  otherwife  removed,  very  little  of  the. 
K  k  3  goldi 


£  ©Id  can  1  e  extracted.  The  reparation  will  alfo  (v- 
promoted  by  the  addition  of  fulphurcous  lubftances. 

From  thefe  conlideracions,  the  Baron  lays  down  the 
following  rules  concerning  amalgamation. 

"  i.  The  or&s  and  mixtures  previous  to  their  amal 
gamation  rnuft  be  mechanically  comminuted,  and  re 
duced  to  a  fine  powder,  by  Ramping,  grinding-,  and 
fifting,  that  the  iurfaccs  of  the  particles,  and  their 
points  of  contact,  may  be  increafed  and  multiplied. 

"  2.  This  powder  muft  be  calcuied,  that,  beiides  the 
pure  particles  of  the  nobler  metals,  thofe  which  ara 
difguifed  in  the  ore  may  be  difengaged  and  laid  bare 
by  deful'phuration  and  calcination. 

"  3.  If  before  its  calcination  no  common  fait  was 
added,  it  muft  be  added  afterwards  ;'  then  it  mufl  be- 
triturated  with  a  proportionate  quantity  of  qmcklilver 
and  water,  long  enough,  arid  in  fuch  a  manner,  that 
the  quicklilver,.  by  an  uninterrupted  motion  of  the 
e  mafs, ..may  come  Into  repeated  cc>iitac'ri:  \vi'..h  the 
difengaged  gold  and  filler  particles,  and  take  them 
up. 

*'  4.  As.much  depends  onthe  jufc-mentioned  propor 
tions,  the  -infpcclor,  diredor,  or  maftcr  of  the'  work,, 
muft  be  well  acquainted  with  the  elefHve  attraction  of 
bodies,  that  forming  a  jilft  idea  of,  ar.d  judgment  on^ 
their  different  mechanical  or  chemical  decompofitioa 
and  combination,  he  may  remedy  and  remove Tuch  un-. 
tovrard  .difficulties  and  impediments  in  the  prcceis  as 
may,  and  willfometimes,  .prevent  its  fall  fuccefs." 

The  vaiious  fteps  by  which  the  metals  are  extracted1 
from  their  ores,  according  to  the  Baron's  method,  are,, 
i.  Stamping,  grinding,  and  fitting.  2.  Calcination^ 
sfter  which  the-grinding  and  fiftirg  muft  be  repeated. 
3.  Triturp.tion  4. .  Wafhing  of  the  refiduurn.  5,  K- 
liqnatibn  of  the  amalgama.  6.  He?jting  of  the  fame, 
7  D\  ft  illation  of  the  quickfilver  preffed  from  the  amal 
gam.  8,.  Refining  of  the  heated  amalgam.  9.  Ex-. 

tracling 


t    4QI     3 

tnicting  from  the  refidua  fuch  parts  of  the  noble  me 
tals  as  may  it  ill  be  contained  in  them. 

1.  Stamping,  grinding,  and  Jiftiag.  The  Baron  reccm- 
men  .s  dry  ftamps  and  mills  for  this  purpofe  ;  as  wet- 
ftarnps,  he  fays,  "  would  bring  on  great  lofs  of  filver 
and  expenfive  coiitnv-.-inces  to  prevent  or  recover  it." 
On  the  other  hand,  E.   Rafpe,  the  tranflator  of  his 
voile,  fays,   that  "  late  experiments  have  proved  fo 
much  in  favour  of  the  wet  ftamps,  that  they  have  ac- 

.tually  been  adopted  as  great  improvements." 

Tjie  contents  of  the  ores  are  accurately  inveftigated 
by  etiays  beibre  any  thing  is  done  in 'the  large  way. 
The  ores  are  delivered  to  the  refpective  mills ;  the 
fmuller  ores  are  pafied  over  a  brafs  fieve,  the  mefhes  of 
which  are  about  one-tenth  of  an  inch  wide,  that  the 
finer  particles  may  be  feparated  and  not  lent  to  the 
ftamps,  which  would  occafion  fome  wafte,  eipecially 
in  the  dry  way.  The  finer  fane!  is  fent  direcliy  to  the 
mill,  and  the  big  lumps  to  the  ftamp.  Each  box,  &• 
fet  of  ftamps,  has  three  ftamp-heads,  weighing  40  or 
54  pounds,  the  fole  being  of  call-iron.  The  matter 
is  every  now  and  then  wetted  with  water  to  pie- 
vent  the  finer  parts  from  flying  off.  When  the  ore  is 
fuihciently  beat  in  the  ftamps,  it  is  afterwards  fifted, 
and  the  coarfe  part  returned  to  the  ftamp.  When  the 
coarfeft  part  is  reduced  in  this  manner  to  the  fr/e  of 
coarfe  fand,  it  is  fent  to  the  mill ;  the  running  ftone  of 
which  muft  be  kept  clofe  in  a  box,  and  nothing  left 
open  but  the  admiffion-fannel.  The  millftones  are  a, 
kind  of  porphyry,  and  the  lieves  of  brafs-wire. 

2.  Calcination.  The  ore  being  reduced  to  a  fuffideht 
degree  of  nneriefs,  is  next  carried  to  the  calcining  fur 
nace  ;  previous  to  which  it  is  again  to  be  tried  by  ef- 
fay,  and  to  have  the  proper  additions  according  to  its 
nature.     When  the  furnace  is  properly  heated,   the 
whole  quantity  of  ore  deftined  to  one  furnace,  about 
30  quintals,  is  brought  up  to  the  top  by  wheel-bar- 
rows  \  and  being  fpread  as  even  as  may  be,  the  proper 

cruamitv 


quantity  of  fait  and  lime  is  fifted  over  it  ;  and  the 
whole  turned  with  crooks  and  rakes  till  it  be  perfectly 
mixed.  The  calcination  is  then  performed  in  the  fol 
lowing  manner:  The  back-door  be'ng  carefully  ihut, 
eight  hundred  weight  of  the  matter,  prepared  as  al 
ready  mentioned,  is  let  down  through  a  funnel  upon 
the  upper  hearth.  Here  it  is  again  to  be  ipread  and 
allowed  to  dry  before  it  is  put  down  on  the  lower 
hearth  ;  and  as  foon  as  this  is  done,  another  quantity 
iS  put  upon  the  upper  hearth,  that  the  two  operations 
may  regularly  fucceed  each  other. 

Our  author  defcribes  at  great  length  all  the  minu- 
tiiE  of  this  operation  :  but,  as  he  jultly  obferves,  "  Ex 
perience  and  practice  are,  and  omit  be,  the  beft  teach 
ers  ;  [or  triers  are  many  things  which  iniilt  be  attended 
to,  and  which  words  and  defcriptions  will  hardly  make 
intelligible."  We  fhaH  therefore  only  obferve,  that  the 
calcining  furnace  mult  be-L-epr  ne/ited  day  and  night  : 
but  while  the  ore  is  fir  wed  down  from  the  upper  to 
the  lower  hearth,  the  fire  mud  bt-  kept  very  moderate  ; 
and  during  the  calcination  it  will  be  neceifary  to  keep 
the  matter  conftantry  turning  w  tn  iron  rakes,  the 
combs  or  teeth  of  which  are  from  four  to  eight  inches 
long. 

The  grinding  and  fifting  after  calcination  is  only 
neceifary  when  the  matter  has  run  into  hard  indiflb- 
luble  clots  during  the  operation  ;  and  is  performed  in  a 
grinding  and  fifting  mill,  which  turns  by  water  ;  but 
which  is  unneceifary  here  to  defcribe,  as  every  pof- 
feifor  of  mines  wruld  chcofe  fuch  mechanical  contri 
vances  as  beft  fuithis  purpofe. 

3.  Tnturatlony  bo'ling,  and  amalgamation.  After  the 
ores  have  bren  prcperly  calcined  and  pounded,  the 
fuccefs  of  the  amalgamation  depends  moftly  on  the 
proportions  of  quickiilver  and  water  which  are  added 
to  the  ftufF,  and  the  construction  of  the  ftirring  appa 
ratus  by  which  the  whole  is  kept  in  conttant  motion 
and  mutual  contact.  The  lighter  the  fluff,  the  mere 

voluminous: 


C    403    3 

voluminous  and  bulky  it  will  prove,  and  confequentlj 
the  g^ld  and  filver  will  be  nv  re  difperfed  ;  in  which 
cafe  the  quantity  of  quickfilver  mult  be  proportioned 
to  the  mvifs,  that  not  with  it  an  ding  its  conftant  gravita 
tion  towards  the  bottom  it  may  th?  more  frequently 
come  in  contact  with  the  gold  and  filver.  It  acts  in 
pro portion  to  its  bulk  and  fur  face.  A  larger  quantity 
is  therefore  advifeable,  as  it  not  only  frrms  a  larger 
furiace  on  the  bottom  of  the  veflel,  but  comes  likewife 
into  contact  with  the  gold  and  filver  more  frequently  ; 
nor  is  there  any  greater  lofs  of  quickfilver  tn  be  ap 
prehended  on  that  accourfc,  A  larger  proportion  of 
fluid  metal  is  in  particular  neceifary  when  the  matter 
is  mixed  with  lead  or  antimony  :  for,  by  taking  up 
the  lead,  it  becomes  proportionably  lefs  active  and  fit 
for  the  reception  of  gold  and  filver  ;  and  turning  greafy 
by  the  antimony,  it  mull  in  the  former  cafe  leave  rich 
refidua,  and  in  the  latter  bring  on  greater  lofs.  It  is 
alfo  determined  by  experience,  that  the  excefs  of 
quickfilver  never  does  ar.y  hurt,  while  too  faiall  a 
quantity  never  fails  to  be  difadvantageous. 

With  regard  to  the  conftruction  of  the  boilers,  it  is 
needlefs  to  be  particular,  as  th^fe  recommended  by  A- 
lonfo  Barba  feem  to  be  very  adequate  to  the  purpofe. 
Heat  is  required ;  but  it  is  not  necefTary  that  the  mat 
ter  ihould  boil,  a  moderate  fire  being  fufficient  for  ma 
king  the  metals  unite.  Nor  is  there  occafion  for  more 
water  than  what  will  make  the  matter  liquid.  The 
ftirring  apparatus  is  put  in  motion  by  the  crank  of  a 
water  wheel,  and  a  horizontal  rack  with  cogs ;  which 
being  properly  fixed  in  a  groove  by  crofs  bars,  Hides 
forward  and  backward  on  brufs  rollers  and  cafiersl 
The  cogs  of  this  rack  catch  into  thofe  of  the  perpen 
dicular  trundle  and  fpindle  of  the  Rirrers,  which  turns 
round  twice  by  three  and  an  half  feet  motion  of  the 
Hiding  rack.  The  whole  moves  quicker  and  flovrer  in 
proportion  to  the  box  of  water  thrown  upon  the  wheel ; 
&nd  the  quicker  motion  oftliQ  rack  produces  of  courfe 

a  quick 


4°4 

a  quick  turn  and  better  trituration.  The  ftirrers  midt 
be  circular  fcgments  correfponding  with  the  fides  and 
bottom  of  the  boiler,  otherwife  their  motion  is  irre 
gular  and  urif.vtisfaclory.  The  time  of  trituration,  as 
depending  on  the  nature  of  the  ore,  muft  be  deter 
mined  by  experience. 

4.  The  wajh'utg  of  the  triturated  leavings  or  refidunm 
is  performed  in  large  tubs,  and  requires  no  particular 
defcription,  farther  than  that  it  be  continued  till  all  the 
fcluble  matter  be  got  out ;  and  for  this  purpofe  there 
mu (I  be  a  contrivance  for  ftirring  the  matter  all  the 
time  it  is  waihing. 

5.  E ^iquation  of  tie  qmckji!*ver  and  amal^ama.      For 
merly  this  was  performed  in  bags  made  of  deer-lkins, 
ftrongly  comprefled  with  engines  for  the  purpofe  ;  but 
this  being  found  too  expenfive,  it  is  now  done  by  fmall 
quantities  at  a  time,  and  prefled  only  by  the  hand  till 
the  ball  of  amalgam  yields  no  more  quickfilver.     A 
fmall  quantity  always  remains  in  the  quickfilver  which 
pafles  through  ;  and  this  quantity  is  the  greater  in  pro 
portion  to  the  warmth  of  the  amalgam  when  prefled. 

6.  The  (Vijl'iUation  of  ike  amalgam   is   performed  per 
defcenfum  in  large  irm  pots.     The  undermoft  ftands 
upright  to  its  middle  in  a  ft  ream  of  cold  running  wa 
ter  which  paries  under  the  hearth  ;  the  upper    part 
h,<;rdly  appearing  two  inches  above  it.  The  amalgam, 
made  up  into  balls,  is  placed  in  iron  cullenders  fixed 
upon  a  tripod  let  in  the  bottom    of  the  lower  pot, 
and  covered  in  the  infide  with  a  coarfe  cloth.     The 
upper  pot  is  inverted  on  the  lower  one  ;  and  the  junc 
ture  being  luted,  the  fire  is  put  all  round  the  outer 
one,  and  the  heat  pafilnpr  through  to  the  amalgam 
quickly  liquefies  it,  and  raifes  the  quickfilver  in  vapour, 
which  condenfes  in  the  under    pot  continually  kept 
cool  by  the  ftream  of  water.     The  upper  pot  is  kept 
in  a  (trong  red  heat  for  five  or  fix  hours  ;  by  which 
means  the  cloth  is  entirely  converted  into  tinder,  fo 
that  the  cullenders  muft  afterwards  be  cleaned  with  a- 
brafii  brufh, 

The 


C    4^5    ] 

The  other  operations  contain  nothing  particular  but 
what  may  he  eafily  uudcniood  from  what  has  been  al 
ready  delivered. 


SECT.  IV.     Ores  of  Copper. 

§  i.  COPPER  is  found  under  ground  in  three  diffe 
rent  forms:  i.  Native  or  virgin  copper  diverfely  ra 
mified,  which  is  much  more  rare  tnan  native  fiiver. 
This  native  copper  is  not  ib  ductile  as  copper  purified 
by  fufions  tro.n  the  ore  (A).  2.  Copper  is  found  in: 
form  of  calx,  of  verdigrife,  of  precipitates.  Such 
are  the  minerals  called  ftlky  copper  ores,  and  feveral 
whit:  and  green  earths.  Theie  matters  are  only  cop« 
per  almoft  pure  and  but  little  mmeralifed,  but  which 
has  been  corroded,  diJf>lved,  precipitated,  calcined  by 
faline  matters,  by  the  aclion  of  the  air,  of  water,  and 
of  earths  (B).  3.  Copper  is  frequently  in  a  truly  mi 
neral  ftate,  that  is,  combined  with  iVdphur  and  with 
arfenic,  with  other  metallic  matters  mixed  with  earths, 

and 


(A.)  Native  copper  is  folid  ;  or  confuting  of  friable 
maifes,  formed  by  precipitation  of  cupreous  vitriolic 
waters  called  cement,  or  •ziment  copper  ;  or  forming  cry- 
ftallifed  cubes  or  grains,  leaves,  branches,  or  filaments. 

(B)  Calc'tform  ores  are  either  pure  calxes  of  copper, 
or  are  mixed  with  heterogeneous  matters,  i.  The 
pure  or  loofe  friable  ochre,  called  aeruleum  montanum 
"  mountain  blue,"  and  virtde  mantanum  "  mountain- 
green  ;"  and  the  red  indurated  calx,  called  improperly 
g/afs.  copper  ore.  2.  Mixed  calciform  ores  are  thofe  in 
Wuich  the  calx  of  copper  is  mixed,  with  calcareous  earth, 
forming  a  mountain-blue  ;  with  iron,  forming  a  black 
calx  ;  with  g  pfum,  an  indurated  green  ore,  called  ma/a- 
i  aod  with  quartz,  a  red  ore. 


[    4o6    ] 

and  enveloped  in  different  matrices  (c).  Thefe  are  the 
true  copper  ores.  They  have  no  regular  forms  ex 
cept  they  partake  of  the  nature  of  pyrites.  Their  co 
lours  are  very  different,  which  depend  chiefly  on  the 
proportion  of  the  mineral  fubilancts  c^-mpoiing  them. 
JL.afl.ly,  in  almoft  all  of  them  we  may  perceive  green 
or  blue  colours,  which  always  indicate  an  erofion  <  T  cal 
cination  of  the  copper.  Moft  copper  ores  contain  alia 
fome  iron  or  ferruginous  earth,  to  which  the  ochrey 
colour  is  to  be  attributed,  which  might  make  us  believe 
them  to  be  ores  of  iron.  Ores  which  contain  much  iron 
are  the  moft  difficultly  fufible. 

Copper 


(c)  Copper  is  mineraltfed,  I.  By  futybur,  forming 
tilt  grey  copper  ore,  improperly  called  vitreous  (minera 
cupri  vitrea  Wallerii).  2.  By  fulplmrated  Iron,  form 
ing  the  hepatic  copper  ore  (minera  cupri  hepatica  Wal 
lerii)  of  a  brown  yellow  colour.  It  is  a  kind  of  cu 
preous  pyrites,  and  is  called  by  Cronftedt  minera  cupri 
pyrit-acea.  Sometimes  it  is  of  a  blackifh  grey  colour, 
and  is  then  called  pyrites  cupri  grift  us  (minera  cupri 
grifea  Wallerii )  ;  fometimes  of  a  reddifh  yellow,  and 
tarniihed  with  blue  iriies  on  its  furface,  when  it  is  call 
ed  minera  cupri/a  xiirea  ;  when  of  a  yellowifh  green  co 
lour,  it  is  thcpyrittt  cupri  jlavo-viridefctns  (cuprum  ful- 
phure  et  ferro  mineralifatum  WalleriT)  j  and  when  of 
a  pale  yellow  colour,  it  is  the  pyrites  cupre  pallid e  Jta<uus. 
Moft  of  the  above  pyritaceous  ores  contain  alfo  fome 
arfenic,  but  their  iulphur  is  predominant.  3.  Copper  mi- 
neralijed  by  jujphur,  iron,  and  arjenic.  White  copper  ore 
(Minera  cupri  alba  Wallerii).  This  ore  contains  alfo 
fome  filver.  4.  Copper  diffohed  by  vitriolic  acid.  Na 
tive  blue  -vitriol.  5.  Copper  united  with  bitumens.  Cup 
per-coal  ore.  This  is  a  pit  coal,  from  the  afhes  of 
which  copper  is  obtainable.  6.  Copper  is  alfo  found 
-in  the  mineral  called  kuffer  nickel. 

4 


t    407    3 

Copper  ores  have  aimed  all  a  yellow,  golden,  and 
fhiniag  colour,  by  which  they  are  eafily  diftinguifned. 
Some  of  them  are  coloured  with  irifes,  and  frequently 
have  fpots  of  verdigrife,  by  which  alfo  they  are  diftin- 
gui  ill  able  from  other  ores. 

Many  copper  ores  are  alfo  rich  in  filver.  Such  is 
that  called  the  white  copper  ore.-,  the  colour  of  which 
is  rather  occafioned  by  arfenic  than  by  filver,  although 
it  contains  fo  much  filver  as  to  be  enumerated  by  ie- 
veral  mineralogifts  amongft  filver  ores. 

Laftly,  the  pyrites  of  a  golden  yellow  colour  which 
contains  copper  and  fulphur,  and  the  white  pyiite* 
which  contains  copper  and  arfenic,  are  confidered  as 
copper  ores  by  feveral  chemifts  and  naturalifts.  Henc- 
fcel  and  Cramer  remark,  that  no  proper  ore  of  copper 
is  known  which  does  not  contain  a.  confiderable  qaan- 
tity  of  arfenic. 

§  2.  Ores  of  copper  may  be  effayed  in  methods  fimi- 
larto  thofe  employed  for  fmelting  of  large  quantities 
of  ores  (Part  III.},  or  they  may  in  general  be  eflay-ed 
fey  the  following  procefTes. 

PROCESS      I. 

'To  reduce  and  precipitate  copper  from  a  pure  and  fujillt 
ort  in  a  clofe  vefeh 

"Mix  one,  or,  if  you  have  fmall  weights,  two  do- 
cimaftical  centners  of  ore  beat  extremely  fine,  with  fix 
centners  of  the  black  flux  ;  and  having  put  them  into 
a  crucible  or  pot,  cover  them  one  inch  high  with  com 
mon  fait,  and  prefs  them  down  with  your  finger :  but 
let  the  capacity  of  the  veiTel  be  fuch  that  it  may  be 
only  half  lull ;  ihut  the  veflel  clofe,  put  it  into  the  fur 
nace  ;  heap  coals  upon  it,  fo  that  it  may  be  covered 
over  with  them  a  few  inches  high  ;  govern  the  fire  in 
ibch  a  manner  that  it  may  fir  ft  grow  flightly  red-hot. 
L 1  Sooa 


C    4Q*    3 

Soon  after  you  will  hear  your  common  fait  crackle; 
and  then  there  will  be  a  gentle  hifling  noife.  So  long 
as  thislafts,  keep  the  fame  degree  :of  fire  till  it  is  quite 
over.  Then  increafe  fuddenly  the  iiie,  either  with 
the  funnel  and  cover  put  upon  the  furnace,  or  with  a 
pair  of  bellows  applied  to  the  hole  of  the  bottom  part, 
that  the  veffel  may  grow  very  red  hot.  Thus  you  will 
reduce  and  precipitate  your  copper  in  abour  a  quarter 
of  an  hour :  then  take  out  the  veffel,  and  ftrike  with 
a  few  blows  the  pavement  upon  which  you  put  it,  that 
all  the  fmall  grains  of  copper  may  be  collected  in  one 
mafs. 

"  Break  the  veflfel,  when  grown  cold,  in  two,  from 
top  to  bottom,  as  nearly  as  you  can  :  if  the  whole  pro- 
cefs  has  been  well  performed,  you  will  find  a  folid,  per 
fectly  yellow  and  malleable  regulus  adhering  to  the 
bottom  of  the  veffel,  with  fcorias  remaining  at  top  of 
a  brown  colour,  folid,  hard,  and  fhining,  from  which 
the  regulus  muft  be  feparate.d  with  feveral  gentle  blows 
of  a  hammer;  this  done,  weigh  it,  after  having  wiped 
oiFallthefilthinefs. 

A  foft,  dufty,  and  very  black  fcoria,  is  a  fign  of  a 
fire  not  fufficiently  ftrong.  Small  neat  grains  of  cop 
per  reduced  but  not  precipitated,  and  adhering  ftill  to 
icorias,  efpecially  not  very  far  from  the  bottom,  an4 
an  unequal  and  ramificated  regulus,  are  figns  of  the 
fame  thing.  A  folid,  hard,  (hining,  red-coloured 
fcoria,  efpecially  about  the  regulus,  or  even  the  regu 
lus  itfelf  when  covered  with  a  like  fmall  cruft,  are 
figns  of  an  excefs  in  the  degree  and  duration  of  the 
fire. 

"  Remarks.  All  the  ores  which  are  eafily  melted  in 
the  fire  are  not  the  objecls  of  this  procefs  ;  for  they  muft 
alfo-be  very  pure.  Such  are  the  vitreous  copper  ores." 
(Mr  Cramer  means,  it  is  prefumed,  the  red  calciform 
ere,  called  improperly  glafs  ore,  and  not  the  mlnera 
cupn  intrea  of  Wallerius,  which  being  compofed  of  cop 
per  mineralifed  by  fulphur  could  not  be  treated  pro 
perly 


t  409   ] 

perly  by  this  procefs,  in  \vhich  no  previous  roafling  is 
required.  The  fulphur  of  this  ore  would  with  the  al 
kali  of  the  black  flux  form  a  hepar,  from  which  the 
metal  would  not  precipitate).  "  But  efpecially  the 
green  and  azure-coloured  ores,  and  the  cteruhum  and 
•vlride  montanurfi)  which  are  not  very  different  from 
them.  But  if  there  is  a  great  quantity  of  arfenic,  ful 
phur,  or  the  ore  of  another  metal  and  femimetal  joined 
to  the  ore  of  copper,  then  you  will  never  obtain  a  mal 
leable  regulus  of  pure  copper,  tho'  ores  are  not  always 
rendered  refradory  by  the  prefence  of  thefe." 

PROCESS     II. 

70  reduce  and  precipitate  copper  out  of  ores  rendered  refrac 
tory  by  earth  andjlones  that  cannot  be  wafiedojf. 

j 

"  BEAT  your  ore  into  a  moft  fubtile  powder,  of  which 
weigh  one  or  two  centners,  and  mix  as  much  fandiver 
to  them.  This  done,  add  four  times  as  much  of  the 
black  flux  with  refpeft  to  the  ore ;  for  by  this  means, 
the  fterile  terreftrial  parts  are  better  difpofed  to  a'fcori- 
fication,  and  the  reducing  and  precipitating  flux  may 
aft  more  freely  upon  the  metallic  particles  freed  from 
all  their  incumbrances. 

"  As  for  the  reft,  make  the  apparatus  as  in  laft  pro 
cefs  :  but  you  muft  make  the  fire  a  little  ftronger  for 
about  half  an  hour  together.  When  the  vefTel  is  grown 
cold  and  broken,  examine  the  fcorias,  whether  they  are 
as  they  ought  to  be.  The  regulus  will  be  as  fine  and 
ductile  as  the  foregoing. 

"  Remarks.  As  thefe  copper  ores  hardly  conceal 
any  fulphur  and  arfenic  in  them,  the  roafting  would  be 
of  no  effeft,  and  much  copper  would  be  loft.  For  no 
metallic  calx,  except  thofe  of  gold  and  iilver,  improper 
ly  fo  called,  can  be  roafted,  without  you  find  a  part  of 
the  metal  loft  after  the  reduction." 

L  1  2  PROCESS 


t     41®     ] 

PROCESS     III. 

To  precipitate  copper  out  of  an  ore  (D)  that  contains 


-•"  Do  all  according  to  laft  procefs.  But  you  will 
find  after  the  vefJ'el  is  broken,  a  regulus  upon  no  ac 
count  fo  fine,  but  Icfs  ductile,  wherein  the  genuine  co 
lour  of  the  copper  dees  not  perfectly  appear,  and  which 
muft  be  further  purified. 

J  "  Remarks.  The  fire  ufed  in  this  operation  is  not 
fo.  ftrong  that  the  iron  mould  turn  to  a  regulus.  But 
as  copper  is  the  menftruum  of  iron,  which  is  of  itfelf 
\ery  refractory  in  the  fire  ;  for  this  reafon,  while  the 
ore  and  the  flux  are  moft  intimately  mixed  and  con 
founded  by  trituration,  the  greateft  part  of  the  iron  be 
ing  diiiblved  by  the  copper,  turns  into. a  regulus  along 
Vvith  it," 

PROCESS    IV. 

The  roajllng  of  a  pyritofe,  fulpbur£ous9  arfenical,  fenume» 

tallic,  copper  ore. 
. 
"  BREAK  two  docimaftical  centners  of  the  ore  to  a 

ccarfe  powder,  put  them  into  a  teft  covered  with  a 
tile,  and  place  them  under  the  mufHe  of  a  doctmaftical 
furnace.     But  the   fire  muft  be   fo   gentle,  that  the  • 
muffle  may  be  but  faintly  red-hot.     When  the  ore  has  . 
decrepitated,  open  the  teft  and  continue  the  fire  for  a. 
few  minutes  ;  thqn  increafe  it  by  degrees,  that  you  mayi 
fee  the  ore  perpetually  fmoking  a  little:  in  the  mean 
time,  it  is  alfo  proper  row  znd  then  to  ftir  it  up  with  . 
an  iron  hook.     The  fhining   particles  .will  alTume  a* 

dark 


(D)  Mr  Cramer  ftill  means  the  calciform  ores  only,  ; 
and  not  the  rnineralifed  ores  of  copper, 


C     4»     3 

dark  red  or  black ifh  colour.  This  done,  take  out  the 
left,  that  it  may  grow  cold.  If  the  fmall  grains  are 
not  melted,  nor  Itrongly  adherent  to  each  other,  hi 
therto  all  will  be  well ;  but  if  they  run  again  into  one 
fmgle  c  ike,  the  procefs  muft  be  made  again  with, 
another  portion  of  the  ore,  in  a  more  gentle  lire. 

"  When  the  ore  is  grown  cold,  beat  it  to  a  powder 
fomewhat  finer,  and  roaft  it  by  the  fame  method  as  be 
fore  ;  then  take  it  out,  and  if  the  powder  is  not  melted 
yet  beat  it  again  to  a  moft  fubtile  powder  j  in  this  you 
are  to  take  care  that  nothing  be  loft. 

**  Roaft  the  powder  in  a  fire  fomewhat  ftronger. 
but  for  a  few  minutes  only.  If  you  do  not  then  find 
the  ore  any  way  inclined  to  melt,  add  a  little  tallow 
and  burn  it  away  under  the  muffle,  and  do  the  fame 
another  time  again,  till,  the  fire  being  very  bright^ 
you  no  Ipnger  perceive  any  fulphureous,  arfenical,  un- 
pleafant  I'm  ell,  or  any  fmoke  ;  and  there  remains  no 
thing  but  a  thin,  fofr  powder,  of  a  dark  red,  or  black- 
ifh  colour. 

"  Remarks.  Every  pyrites  contains  iron,  with  an, 
unmetallic  earth ;  to  which  fulphur  or  arfenic,  and 
moft  commonly  both,  always  join.  Befides,  there  is 
copper  in  many  pyrites  ;  but  fometimes  more  and  fome- 
limes  lefs :  fome  of  them  are  altogether  deftitute  of 
copper ;  therefore,  fo  much  as  pyrites  differ  with  re 
gard  to  the  proportion  of  their  conftituent  particles,  fo 
much  do  they  differ  as  to  their  difpofition  in  the  fire* 
For  inftance,  the  more  copper  there  is  HI  pyrites,  the 
more  it  inclines  to  colliquation.  The  more  fulphur 
and  arfenic  it  has  in  it,  the  more  quickly  the  melting 
of  it  will  be  procured,  and  the  reverfe  :  the  more  iron 
and  unmetallic  earth  it  contains,  the  more  it  proves  re- 
fra&ory  in  the  fire.  Now  if  fuch  pyrites  melt  in  the 
roafting,  as  happens  to  fome  of  them  if  they  grow  but 
red-hot,  the  fulphur  and  arfenic  that  lies  hidden  therein 
are  fo  rtri&ly  united  with  the  fixed  part,  that  you 
would  in  vain  attempt  to  diffipate  them.  Nay,  in  this 
LI  5  caf 


C    4«2    3 

"cafe,  when  it  is  reduced  again  into  a  powder  it  re- 
a  much  greater  time  and  accuracy  in  the  regimen  of  the 
fere  to  perform  the  operation.  For  this  reafon,  it  is 
tnuch  better  to  repeat  it  with  new  pyrites.  But  you 
can  road  no  more  than  the  double  quantity  at  once  of 
the  ore  you  have  a  mind  to  employ  in  the  foregoing 
experiment.;  to  the  end  that,  the  precipitation  by  fufion 
*lict  fucceeding,  there  may  remain  dill  another  portion 
entire  ;  left  you  fhould  be  obliged  to  lepeat  a  tedious 
reading.  If  you  fee  the  figns  of  a  ferreous  refractory 
pyrites,  the  operation  mud  be  performed  with  a  greater 
fire,  and  much  more  quickly.  However,  take  care 
not  to  do  it  with  too  violeRt  a  fire :  for  a  great  deal  of 
copper  is  confumed  not  only  by  the  arfenic,  but  alfo 
by  the  fulphur ;  and  this  happens  even  in  veflels  flint 
very  clofe,  when  the  fulphur  is  expelled  by  a  tire  not 
quite  io  itrong  ;  which  a  reiterated  and  milder  fubli- 
mati<  n  of  the  fulphur  in  a  veflel  both  very  clean  and 
well  elf  fed  will  clearly  (how. 

"  When  the  greatef;  part  of  the  fulphur  and  the 
arfenic  is  diffipated  by  fuch  caufes  as  promote  colli- 
quation,  you  may  make  adrongerfire  :  but  then  it  is 
proper  to  add  a  little  of  fome  fat  body ;  for  this  dif- 
folves  mineral  fulphur  :  it  changes  the  mixture  of  it  in 
fome  part,  which,  for  indance,  confiils  in  a  certain 
proportion  of  acid  and  phlogifton ;  and  at  the  fame 
time  hinders  the  metallic  earth  from  being  reduced 
into  copper,  by  being  burnt  to  an  excefs.  From  thefe 
effecls,  the  reafon  is  plain  why  aflayers  produce  lefs 
metal  in  the  trying  of  veins  of  copper  lead,  ar.d  tin, 
than  (kilful  fmelters  do  in  large  operations.  For  the 
former  perform  the  roafling  under  a  muffle  with  a 
clear  fire,  and  without  any  oily  reducing  menftruum  ; 
whereas  the  latter  perform  it  in  the  middle  of  charcoal 
or  <'f  wood,  which  perpetually  emit  a  reductive  phlo- 
gidon. 

"  The  darker  and  blacker  <he  powder  of  the  roafted 
-ere  appears,  the  more  copper  you  may  expect  from  it. 

But 


[     4-3     3 

But  the  redder  it  looks,  the  lefs  copper  and  the  more 
iron  it  affords  ;  for  roailed  copper  dilfolved  by  fujphur 
or  the  acid  cf  it,  is  very  black,  and  iron,  on  the  con 
trary,  very  red. 

PROCESS    V. 

The  precipitation  of  copper  out  of  roafted  ore  of  the  Ja$ 

process. 

"  DIVIDE  the  roafted  ore  into  two  parts:  each  of 
them  ihall  go  for  a  centner  :  add  to  it  the  fame  weight 
of  fandiver,  and  four  times  as  much  of  the  black  flux, 
and  mix  them  well  together.  As  for  the  reft,  do  all 
according  to  the  procefs  I :  the  precipitated  regulus 
will  be  half  malleable,  fometimes  quite  brittle,  now 
and  then  pretty  much  like  pure  copper  in  its  colour, 
butfometimes  whitilh,  and  evenblackiih.  Whence  it 
is  moil  commonly  called  Hack  copper,  though  it  is  not 
always  of  fo  dark  a  dye. 

"  It  is  eafy  to  conceive,  that  there  is  as  great  a 
difference  between  the  ieveral  kinds  of  that  metal  call 
ed  Hack  ccpper,  as  there  is  between  the  pyritofe  and 
other  copptr  -.res  accidentally  mixed  with  other  me 
tallic  and  femi-metallic  bodies.  For  all  the  metals, 
the  ores  of  which  are  intermixed  with  the  copper  ores 
being  reduced,  are  precipitated  together  with  the 
copper  which  is  brought  about  by  means  of  the  black 
flux.  Wherefore  iron,  lead,  tin,  the  regultne  part  of 
antimony,  bifrouth,  me  ft  commonly  are  mixed  with 
black  copper  in  a  mu'.tLtu.ie  of  different,  proportion?. 
Nay,  it  is  felf-evident,  that  gold  and  fiH'er,  which  are 
difiulvable  by  all  thefe  mitters,.  are  collected  in  >fuch 
-a  reguius  when  they  have  been  firft  hidden  in  the 
ore.  Belides,  fulphur  and  arfe»ic  are  not  always.alto- 
gether  abfent.  For  they  can  hardly  be  expelled  fo 
perfectly  by  the  many  preceeding  roaftings,  but  there 
remains  feme  vetliges  of  them,  which  are  not  diffipated 

"by 


C    4H     C 

by  a  fudden  melting,  efpecially  in  a  clofe  vefiel, 
wherein  the  flux  fwimming  at  top  hinders  the  action 
of  the  air.  Nay,  arfenic  is  rather  fixed  by  the  black 
flux,  and  afTume's  a  regulinefemi-metallic  form,  while 
it  is  at  the  fame  time  preferved  from  diffipating  by  the 
copper. 

PROCESS     VI. 

To  reduce  black  copper  Into  pure  copper  ly  fcor'ificatlon. 

*'  SEPARATE  a  fpecimen  of  your  black  copper,  of 
the  weight  of  two  fmall  docimaftical  centners  at  leaft  ; 
and  do  it  in  the  fame  manner,  and  with  the  fame  pre 
cautions,  as  if  you  would  detect  a  quantity  of  iilver  in 
black  copper. 

"  Then  with  lute  and  coal-dud  make  a  bed  in  the 
cavity  of  a  teft  moiftened:  when  this  bed  is  dry,  put 
it  under  the  muffle  of  the  docimaftical  furnace,  in  the 
open  orifice  of  which  there  muft  be  bright  burning 
coals,  wherewith  the  teft  muft  likewife  be  furrounded 
on  all  parts.  When  the  whole  is  perfectly  red  hot,  put 
your  copper  into  the  fire,  alone,  if  it  contains  lead ; 
but  if  it  is  altogether  deftitute  of  it,  add  a  fmall  quan 
tity  of  glals  lead,  and  with  a  pair  of  hand-bellows  in- 
creafe  ihe  fire,  that  the  whole  may  melt  with  all  fpeed : 
this  done,  let  the  lire  be  made  a  little  violent,  and  iuch 
as  win  .uffice  to  keep  the  metallic  mafs  well  melted, 
and  not  much  greater.  The  melted  mafs  will  boil,  and 
fcorias  will  be  produced,  that  will  gather  at  the  cir 
cumference.  All  the  heterogeneous  matters  being  at 
lait  partly  diffipated,  and  partly  turned  to  fcorias,  the 
furface  of  the  pure  melted  copper  will  appear,  So  foon 
as  you  fee  it,  take  the  pot  out  of  the  fire,  and  extin- 
guiih  it  in  water:  then  examine  it  in  a  balance;  and 
if  lead  has  been  at  firft  mixed  with  your  black  copper, 
add  to  the  regulus  remaining  of  the  pure  copper  one 
35th  part  of  its  weight  which  the  copper  has  loft  by 

IB  cans 


[    4'5     ] 

means  of  the  lead,  then  break  it  with  a  vice  ;  and  thus 
you  will  be  able  to  judge  by  its  colour  and  malleabi 
lity,  and  by  the  furface  of  it  after  it  is  broken,  whe 
ther  the  purifying  of  it  has  been  well  performed  or  no* 
But  whatever  caution  you  may  ufe  in  the  performing 
of  this  procefs,  the  product  will  neverthelefs  be  always 
lefs  in  proportion  than  what  you  can  get  by  a  greater 
operation,  provided  the  copper  be  well  purified  in  the 
fin  all  trial. 

"Remarks.     This  is  the  laft  purifying  of  copper, 
whereby  the  feparation  of  the  heterogeneous  bodies  be 
gun  in  the  foregoing  procefs  is  completed  as  perfectly 
as  it  poffibly  can  be.     For,  except  gold  and  filver,  all 
tile  other  metals  and  femimetals  are  partly  diffipated 
and  partly  burnt,  together  with  the  fulphur  and  arfe*  ' 
nic.     For  in  the  fufion  they  either  turn  of  themfelves  • 
to  fcoria  or  fumes,  or  this  is  performed  by  means  of  ; 
iron,  which  chiefly  abforbs  femimetals,  fulphur,  and  ar^  ! 
feme,  and  the  deitruclion  of  it  is  at  the  fame  time  ac 
celerated  by  them.     Thus  the  copper  is  precipitated  ' 
out  of  them  pure;  for  it  is  felf-evident,  that  the  un- 
metallic  earth  is  expelled,  the  copper  being  reduced 
from  a  vitrefcent  terreftrial  to  a  metallic  date,  and  the 
arfenic  being  diffipated  by  means  of  which  the  faid 
«arth  has  been  joined  to  the  coarfer  regulufes  of  the 
fir  ft  fufion.    But  there  is  at  the  fame  time  a  good  quan 
tity  of  copper  that  gets  into  the  f:orias :  however,  a 
great  part  of  it  may  be  reduced  out  of  them  by  repeat 
ing  the  fufion. 

"  The  fire  in  this  procefs  muft  be  applied  with  all  • 
imaginable  fpeed,  to  make  it  foon  run  :  for  if  you  ne-  •'• 
gleet  this,    much  of  your  copper  is  burnt;    becaufe  ' 
copper  that  is  only  red-hot,  cleaves  much  fooner,  and 
in  much  greater  quantity,    into  half-fcorified  fcales, 
than  it  is  diminiihed  in  the  fame  time  when  melted.') 
However,  too  impetuous  a  fire,  and  one  much  great 
er  than  is  neceffary  for  the  fufion  of  it  deftroys  a  much 
greater  quantity  of  it  than  a  fire  fufficient  only  to  put  it 


C 

in  fufion  would  do.  For  this  reafon,  when  the  purify 
ing  is  finifhed,  the  body  melted  muft  be  extinguished 
in  water  together  with  the  vefTel,  left,  being  already 
grovvn  hard,  it  ihould  ftill  remain  hot  for  awhile; 
which  muft  be  done  very  carefully  to  prevent  dangerous 
explofions. 

"  The  fcoria  of  the  above  procefs  frequently  con 
tains  copper.  To  extract  which,  let  two  or  three  do- 
cimaftical  centners  of  the  fcoria,  if  it  be  charged  with 
fulphur,  be  beat  to  a  fubtile  powder,  and  mix  it,  either 
alone,  or  if  its  refraftory  nature  requires  it,  with  fome 
very  fufible  common  pounded  glafs  without  a  reducing 
faline  flux,  and  melt  it  in  a  clofe  veffel,  and  in  a  fire 
having  a  draught  of  air;  by  which  you  will  obtain  a 
regulus. 

"  But  when  the  fcoria  has  little  or  no  fulphur  at  all 
in  it,  take  one  center  of  it,  and  with  the  black  flux 
manage  it  as  you  do  the  fufible  copper  ore,  (procefs 
I.)  by  which  you  will  have  a  pure  regulus." 

PROCESS    VII. 

The  following  procefs  is  tranflated  from  Mr  Gellert's 
Elements  of  EJfaying,  and  defcribes  a  new  method  of 
efTaying  ores,  concerning  which,  fee  the  fedion  Of 
EJ/aying  in  general,  p.  338.  col.  2. 

To  ejfay  copper  ores. 

ROAST  a  quintal  of  ore  [in  the  manner  defcribed 
in  procefs  IV.J  •-  add  to  it  an  equal  quantity  of  bo 
rax,  half  a  quintal  of  fufible  glafs,  and  a  quarter  of  a 
quintal  of  pitch :  put  the  mixture  in  a  crucible,  the 
inner  furface  of  which  has  been  previoully  rubbed  with 
a  fluid  pafte  of  charcoal-daft  and  water:  cover  the 
whole  with  pounded  glafs  mixed  with  a  little  borax, 
or  with  decrepitated  fea-falt :  put  a  lid  on  the  cru 
cible,  which  you  will  place  in  an  air-furnace,  or  in  a 
blatt-furnace  •  when  the  fire  lliall  have  extended  to  the 
bottom  of  the  coals,  let  it  be  excited  briikly  during 

half 


C    4*7     3 

, 

half  an  hour,  that  the  crucible  may  be  of  a  brifk  red 
colour :  then  withdraw  the  cruciblev  and  when  it  is 
cold  break  it :  obferve  if  the  fcoria  be  well  made  :  fe- 
parate  the  regulus,  which  ought  to  be  femi-dudile  ; 
and  weigh  it.  This  regulus  is  black  copper ;  which 
muft  be  purified,  as  in  procefs  VI. 

If  the  Ore  be  very  poor,  and  inveloped  in  much 
earthy  and  ftony  matters  ;  to  a  quintal  of  it,  a  quintal 
and  a  half  of  borax,  a  quarter  of  a  quintal  of  pitch,  and 
ten  pounds  of  calx  of  lead  or  minium,  muft  be  added. 
The  calx  of  lead  will  be  revived,  and  will  unite  with 
the  fcattered  particles  of  the  copper,  and  together  with 
t-hefe  will  fall  to  the  bottom  of  the  crucible,  forming  a 
compound  regulus.  When  the  ores  of  copper  are  very 
rich,  half  a  quintal  of  borax  and  a  quarter  of  a  quin 
tal  of  glafs  will  be  fufficient  for  the  reduction.  If  the 
ore  is  charged  with  much  antimony,  a  half  or  three 
quarters  of  a  quintal  of  clean  iron-filings  may  be  ad 
ded  ;  otherwife  the  large  quantity  of  antimony  might 
ckftroy  the  copper,  efpecially  if  the  ore  contained  no 
lead.  If  iron  be  contained  in  copper  ore,  as  in  pyrites,, 
fome  pounds,  of  antimony,  or  of  its  regulus,  may  be 
added  in  the  effay ;  as  thefe  ftibftances  more  readily 
unite  with  iron  than  with  copper,  and  therefore  dif- 
cngagethe  latter  metal  from  the  former. 

PROCESS     VIII. 

To  effay  ores  of  copper  by  humid folution. 

SOME  pyrites  and  ores  contain  fo  fmall  a  quantity  of 
copper,  that  it  cannot  be  feparated  by  the  above  pre 
cedes,  but  is  deftroyed  by  the  repeated  roaftings  and 
fufions.  Thefe,  and  indeed  any  copper-ores,  maybe 
eitayed  by  humid  folution,  or  by  menftruums. 

i.  By  reading  a  fulphureous  ore,  the  fulphur  is 
burnt  or  decompofed,  its  phlogifton  with  part  of  the 

acid 


acid  evaporating,  while  the  remaining  part  of  the  acid 
combines  with  the  metals,  efpecially  with  the  copper 
and  iron  contained  in  the  ore.  Accordingly,  from  an 
ore  thus  roafted,  a  vitriolic  folution  may  be  obtained 
by  lixiviation  with  warm  water,  efpecially  if  the  ore 
has  been  expofed,  during  a  few  days  after  it  has  been 
roafted,  to  a  rnoift  air  ;  as  the  water  thus  gradually  ap 
plied  unites  better  with  the  combination  of  the  metal 
lic  calxes  with  the  concentrated  vituolic  acid  of  the 
fulphur :  but  all  the  copper  is  not  thus  reduced  by  one 
operation  to  a  vitriol.  More  fulphur  mu ft  therefore  be 
combined  with  the  refiduous  ore  by  fufion,  and  mult 
be  again  burnt  off,  that  the  remaining  part  of  the  cop 
per  may  be  attacked  by  fome  of  the  acid  of  the  ful 
phur.  By  repeating  this  operation,  almoft  all  the  cop 
per  and  iron  will  be  reduced  to  a  vitriolic  lixivium, 
from  which  the  copper  may  be  feparated  and  precipi 
tated  by  adding  clean  pieces  of  iron. 

2.  Copper-ores  may  be  more  eaiily  effayed  by  hu 
mid  folution  in  the  following  manner  : 

Road  the  mineralifed  ores  in  the  manner  directed 
in  Procefs  IV.  and  pulverife  them.  If  the  ores  be  cal- 
ciform,  they  do  not  require  a  previous  roafting.  Put 
this  powder  into  a  matrafs  capable  of  containing  ten 
times  the  quantity  of  the  ore ;  pour  upon  the  ore  fome 
water :  fet  the  matrafs  in  a  fand-bath,  that  the  water 
may  boil :  pour  off  the  lixivium  :  add  to  the  refidous 
ore  more  water,  with  fome  vitriolic  or  marine  acid  :  di- 
geft  as  before  in  the  fand-bath,  and  add  this  lixivium 
to  the  former  :  repeat  this  operation,  till  you  find  that 
the  acid  liquor  diflblves  no  more  metal. 

By  adding  clean  plates  of  iron  you  may  precipitate 
the  copper,  which  ought  then  to  be  collected,  fufed 
with  a  little  borax  and  char  coal  dull, 'and  weighed. 

We  may  remark,  that  although  copper  is  not  folu- 
ble  by  a  dilute  vitriolic  acid,  yet  the  calx  of  it  obtained 
by  roafting  the  ore,  and  alfo  the  calcifoim  ores,  are 
readily  foluble  in  that  acid. 

4  3.  Stahl 


3-Stalil  ad'/ifes  to  cilay  copper  ores  byjbpiling  them, 
after  they  have  been  roafted  and  powdjrcd,  in  w:iLcr, 
together  with  tartar  and  common  i'ilt,  or  with' altihi 
and  comnif  n  f  ilt :  but  we  have  not  found  this  meihod 
fo  effectual  as  the  proceeding. 


Dr  FcrJyce's  method  of  cffay'ing  copper  ores,  ly  want 
of  a-->ii'i  rcg'ia.  [Phil.  Tranf.  for  1781,  vol.  Ixxr* 
art.  3.] 

THIS  method  confuls  only  in  pouring  a  quantity  of 
an  aquarcgia  compofed  of  equal  parts  of  the  nitrous 
and  muriatic  acids  upon  a  frnail  quantity  of  the  ore  ill 
powder,  til'  afreili  affiVQo'rrof  the  meiiftruurh  Ihnws  no 
green  or  blue  tinge  ;  by  which  m.ans  all  the  metalline 
paft  of  the  ere  will  be  diiiblvcd.  It  is  then  to  be  'pre 
cipitated  by  means  cf  a  fruition  of  iixed  allali,  or 
volatile  alkali  caiitidully  riiana;.!.\-cl  will  anfwcr  the  fame 
j.urpr-fe.  The  metal  then  i-pp^ars  in  f  -rm  of  a  green 
precipitate  called  ^retn  ixrj'iter ;  but  is  mixed  \vi:h 
v.-hat  ciilcarcr.us  earth  might:  liave  been  contained  in 
rhe  ore  ;  winch  the  acidr,  wotil'd  d5;Tclve,  and  the  fixed 
li  tl-nl;  kind  \var>'ufct!,  vouid  precipitate.  The 
cauftic  volatile  alkali  \vould  not  throw  down  t;:,'s 
earth,  and  is  therefore  to  be  prefeive'J  to  any  other; 
but  care  mu ft  be  taken  to  Ir'c  tl:e  pcirit  of  fatnvation 
very  cxa>51iy  with  it,  :.  s  ;t 

if  added  in   tor,  iiimtitj.     Br  Fbfdyce  ol 

this  green  calx  to  be  diffolred   in  vitriolic  acid,   ;md 
then,  by  adding  a  pi'  •  irdrt   to  the  fblfatibn, 

all  the  copper  c>  c  v»ill  be  dbtailled  ia 

its  metallic  form. 

Tins  method  can  be  fab-eel  to  ro  fall  icy,  unlefs  the 

ore  contains  a  luminous  matter  ;  in  which  cure  feme  of 

^he  earih  of  alnm  wiJl  be.  mixed  with  the  metal,  as  that 

'&  m  the 


earth  will  be  precipitated  by  fixed  alkali,  by  cauftic 
volatile  alkali,  and  by  iron.  This,  however,  may 
very  effectually  be  prevented  by  dillblving  the  green 
calx  iirft  in  volatile  alkali,  and  then  in  vitriolic  acid. 
It  is  even  probable,  that  by  reducing  the  ore  to  a  very 
fine  powder,  and  treating  it  with  cauilic  alkali,  all 
the  metal  might  be  feparated  from  the  ere,  without 
the  trouble  of  uiing  aqua  regia.  For  the  principles  on 
which  this  method  is  conducted,  fee  the  article  CHE- 
MISTRY  pafjlm. 

SECT.     V.     Ores  of  Lead, 

§  i.  LEAD  is feldom  found  native  ( E )  and  malleable. 
Neither,  fays  Mr  Macquer  (F),  is  it  found  in  form  of 
calx  or  precipitate,  as  copper  is,  becaufe  it  is  much 
lefs  liable  to  lofe  its  phlogifticn  by  the  action  of  air  and 
.water :  therefore  almoft  all  lead  is  found  naturally 
mineralifed. 

Lead 


(E)  Cronftedt  doubts  whether  any  native  lead   has 
been  found.  Linnaeus  fays,  he  has  feen  what  externally 
appeared  to  be  fuch. 

(F)  But  he  is  miftaken.     As  lead  unites   ftrongly 
Trith  vitriolic  acid,  we  might  expect  to  meet  ochres  of 
.this  metal  as  well  as  of  copper.     Accordingly  we  find 
force  calciform  ores  of  lead.      i.  A  pure  calx  of  lead, 
in  form  of  a  friable  ochre,  cerujja  native,  found  on  the 
TUT  face  of  galena  ;  or  it  is  indurated  with  a  radiated  or 
.fibrous  texture,  of  a  white  or  yellowifh  green  colour, 

and  refembling  fpar;  it  is  .called  fpatum  flumli, fparry 
leaJ-orS)  and  lead-fpar.  2.  A  calx  of  lead  is  found 
mixed  with  calx  of  arfenic,  forming  the  ore  called 
arfenicatcd  Isad-fpar.  Sometimes  alfo  that  calx  is  mixed 
with  calcareous  earth. 


Lead  is  generally  mmeralifed  by  fulphur  (G).  It$ 
ores  have  a  dark  white,  but  fhining  metallic  colour. 
Thefe  ores,  although  they  form  irregular  mafTes,  are 
internally  regularly  difpofed,  and  item  to  be  compofed 
of  cub-s  of  different  fizes  applied  to  each  other,  but 
not  adherent.  Thefe  ores  are  generally  diftinguiihed 
by  the  name  of  Gakna.  They  commonly  contain  about 
three  quarters  of  lead  and  a  quarter  of  lulphur.  They 
are  accordingly  heavy  and  fuiible,  although  much  lefs 
fo  than  pure  lead. 

Moft  lead-ores  contain  filver ;  none  but  thofe  of  Wil- 
l:ich  in  Carinthiaare  known  to  be  quite  free  from  it : 
fome  of  them  contain  fo  much  of  it,  that  they  ars  con- 
fidered  as  improper  ores  of  filver.  The  fmaller  the 
cubes  of  galena  are,  the  larger  quantity  of  filver  has 
been  remarked  to  be  generally  contained. 

§  2.  Lead  Ores  may  be  effayed,  I.  By  means  of  the 
black  flux,  in  the  manner  directed  by  Mr  Cramer,  as 
follows  : 

"  Let  one  or  more  quintals  of  this  ore  be  grofsly 
powdered,  and  roalled  in  a  teft  till  no  more  fulpureous 
vapours  be  exhaled,  and  then  reduced  to  a  finer  pow 
der  ;  it  is  then  to  be  accurately  mixed  with  twice  its 
weight  of  a  black  flux,  a  fourth  parts  of  its  weight  of 
M  m  2  clean 


(G)  Lead  is  mineralifed,  i.  With  fulphur;  fucli  are 
the  feveral  kinds  of  fteel-grained  and  tefielated  gale- 
n. is,  which  alfo  contain  generally  fome  filver,  2.  With 
fulphura:ed  iron  and  filver.  It  is  fm?-grained  or  tef- 
felated,  and  is  diilinguilhed  from  the  former  by  yielding 
a  black  flag  when  fcoriaed,  whereas  the  former  yields 
a  yellow  ilag.  3.  With  fulphurated  antimony  and 
filver.  Plumbum  Jliliatum  Llnnxi.  Its  colour  is  fimilar 
to  that  of  galena,  and  its  texture  ftriated.  4.  With 
fulphur  and  arfenic.  This  ore  is  foft,  almoft  malleable, 
lead.  From  this  ore  lead  may  be  melted  by  the  flame 
of  a  caudle. 


[       422       ] 

clean  filings  cf  iron  and  of  brrax.     The  mixture  is  to 
•.it  into  a  good  crucible,  or  rather  into  a  tell  ;  it 
3  \y,ifh  a  01  two  or  three 

;rs  of  clecr'.  .  >le  is  to  be 

vf.c.kJ,  and  placed  1.        -  ^  v;hlch  i>  to  be 

SBgdi  with  unli;  tap  of  the 

crucible  (hall  be  covered  with  ;  Lhen 

•  o  be  thrown   upon  tie    unldne. •-.-. -,      .  .1,  ;\n  I  the 

hide  .is   left  to  kindle  .lowly,  ill  .'  e  red- 

:    -t ;   fbon  after  7v'i feii  a   hi  •  pi.  ceeds  .'roin 

'..he  crucible,  which  is  oceaiKn.a  ry  the  rcducl:Jon  of 
the  lead:  the  fame  degree  cf  lire  is  to  be  maintained 
v.'hlle  this  iioife  continues,  iriid  is  afterwards  to  be  iud- 
cienly  increafed,  fo  as  to  make  a  perfect  fufion  ;  in 
which  flate  it  is  to  be  continued  during  a  quarter  of 
an  hour;  after  which  it  is  to  be  extinguished  ;  and  the 
operation  is  then  finiihed."  The  filings  of  in  n  are 
;idded  to  the  fixture,  to  abicrb  the  iuiphur  ;  a  certain 
quantity  of  which  generally  renu.rii.,  united  wii:li  the 
lead-ore,  iiOtwithftandlng  the  roallii:^.  We  need  not 
rearleaft  this  metal  (hall  unite  with  the  lead  and  alter 
:'ts  purity;  bccaufe,  altheugh  the  iuij.-hur  ihould  not 
hinder  it,  theie  two  ir.etals-  cannot  be  united.  The  re- 
fradlory  quality  of  the  iron  dotrs  not  impede  tl;e  iu- 
llon  ;  for  the  union  it  forme  with  the  fulphnr  renders 
kfo  fufible,  that  it  becomes  iti>lf  a  kind  of  iiux.  This" 
addition  ofiionin  the  ciray  of  lead-ores  would  be  u  Te 
le  fs,  if  the  ores  were  fuificieiiily  roafted,  fo  that  no  ful- 
phur  friould  remain. 
'  Or,  2.  By  the  following  process  of  Mr  Gellert. 

u  Mix  a  quintal  of  rcalied  lead-ore  wi  h  a  c-niniT;!  of 
calcined  borax,  half  a  quintal  of  (.'l-.'fs  Hnely  pulvtriied, 
-A  quarter  cf  a  quin.-  ch,  and  as  nn;ch  cf. clean 

iron-flings:   pu!    t;-  .-  l^U)  ?.  crucible  weU«:d 

viih   charcoa-duf!:  and  water:   place  the   crucible  be- 
fl-e  tlie  no'/./.le  of  the  heUr.ws  of  a  for^o,    a::d   v-Len 

i ','    or  jo  n.iriUcs  ;  then 
break  it;  v/hcn  ccld." 


C    4'3    ] 

Some  very  fufible  ores,  fuch  as  the  galena  of  Der- 
bylliire,  may  be  eflayed,  as  large  quantities  of  it  are 
fmelted  without  previous  reading,  and  without  addi 
tion,  merely  by  fufion  during  a  certain  time.  For  this 
purpofe  nothing  more  is  requifite  then  to  keep  the  ore 
melted  in  a  crucible  with  a  moderate  heat  till  all  the 
ililphur  is  deftroyed,  and  the  metal  be  collected.  To 
prevent  the  deftruclicn  cf  any  part  of  the  metal  after 
it  is  feparated  from  the  fulphur,  fome  charcoal  -duft 
may  be  thrown  over  the  ore,  when  put  into  the  cru 
cible:  but  if  the  galena  be  mixed  with  pyrites,  efpe- 
dally  arienical  pyrites,  it  requires  much  reading  and: 
feline  fluxes. 

SECT,  VI.      Tm  Ores. 

§  i.  TIN  is  very  feldom  found  pure,  but  almoft  al 
ways  mineralifecl,  and  chiefly  by  arfenic. 

The  richeit  ore  of  tin  is  of  an  irregular  form,  of  a 
black  or  tamilhed  colour,  and  almoit  the  heavieft  o£ 
all  ores.  The  caufe  of  this  extraordinary  weight  is, 
that  it  contains  much  more  arfenic  than  fuiphur, 
whereas  moft  ores  contain  more  fulphur  than  a<fenic. 

The  moil  common  tin  ore  is  of  the  colour  of  ruft, 
which  proceeds  from  a  quantity  of  iron  or  of  ir;  n-cre 
mixed  with  it.  The  tin-ores  of  Saxony  and  Bohemia 
appear  to  be  all  of  this  kind. 

One  kind  of  tin-ore  is  fcmi-tranfparent  and  like  fpar. 
Laftly,  feveral  kinds  of  garnets  are  enumerated  by  mi- 
neralogiiis  among  tin-ores,  becaufc  they  actually  con 
tain  tin. 

The  county  of  Cornwall,  in  England,  is  very  rich 
in  tin-ores;  and  the  tin  contained  in  them  is  very  pure. 
From  tin-mines  in  the  Eaft  Indies  tin  is  brought,  call 
ed  Malacca  tin.  No  mines  of  tin  have  been  difcovcr 
in  France ;  only  in  Bretagne  garnets  are  found  which 
contain  fume  tin. 

Native  tin  is  faid  to  have  been  found  in  Saxony  and 
M  m  3  Malacca.. 


Malacca.  Its  ores  are  all  of  the  calciform  kind,  ex 
cepting  black-lead,  which  appears  to  be  tin  minera- 
lifed  by  fulphur  and  iron. 

The  calciform  ores  of  tin  are,  i.  Tin  {lone,  which 
is  of  a  blackiih-brown  colour,  and  of  no  determinate 
figure  ;  and  tin-grains,  or  cryftuls  of  tin,  which  re- 
iemble  garnets,  an.!  are  of  a  ipherical  or  polygonal  fi 
gure,  which  they  have  probably  acquired  by  the  attri 
tion  of  their  angles.  The  tin-Hone  feems  to  confift  of 
attrited  tin-grains.  This  ore  is  calx  of  tin  united  with 
calx  of  arfenic,  and  frequently  with  calx  of  iron. 
2.  Garnets  are  laid  to  conuiin  calx  of  tin  united  with 
calx  of  iron.  3.  Manganefe  is  fait!  alfo  to  contain  tin. 

§  2.  Ores  of  tin  m:.<y  le  ej}'\yed  in  the  fame  manner, 
according  to  Cramer,  as  he  directed  for  the  eiiay  of 
3ead-ores,/'./>;w.  Ke  further  m.ikes  upon  this  eiiay  the 
ft  *1 : owi 11  g  rein ar k 5 , 

I.  Tin-ore,  on  account  of  it?  grsateir  gravity,  ad 
mits  better  or  being /ep^r  ifci&H  or  watli- 
ing,  from  earths,  (tones,  .  .      2,  A  moil 
exact  reparation  of  earth1:  .>..  . 
becaufe  the  fcorifica'ao:i  oft                     -    -  re  [ui 
:i  heat  as  wTould  deitroy  t                 _d  tin.      3.  Tlie  ire  a 
ought  to  b?  ieparated  by  a  magnet.     ^..  By  a  previous 
roailir.g,  the  arieaic  is  diffipated,  which  would  o 
wife  cany  oif  a  great  deal  of  tin  al  nig  with  it  in  a  melt 
ing  heat,  would  change  another  part  of  it  into  alhess, 
and  would  vitiate  the  remaining  t'..i,    \.   'ihe  eflay  of 
tin  is  very  precarious  and  uncertain  ;  becaui b  tin  once 
r,duc:d  is  eafily  de.rrucl'ible  by  the   tire,  and  by  the 
faline  fluxes  reqaifite  for  the  reduction. 

Mr  Gellert  aireds,  that  ores  of  tin  Ihoukl  be  eifayed 
in  the  following  manner  : 

"  Mix  a  quintal  of  tin  ore,  wafhed,  pulverifed,  and 
twice  roaftecl,  with  ha-f  a  quintal  of  calcined  borax, 
rand  half  a  quin"a^bf  pulverifed  pitch  :  thefe  are  to  bj 
put  into  a  crucible  rnoiftened  with  charcnal-diUl  and. 
wal;cr,.and  the  crucible  placed  in  an  uir-farnace;  after 

the 


[     4^5     J 

the  pitch  is  burnt,  give  a  violent  fire  uirrmg  a  quarter 
of  an  hour  :  and  men  withdraw  your  criicible.  If  the 

ore  be  not  very  well  wafned  from  the  ea  tiiy  natters, 
as  it  ou^lit  to  be,  a  larger  qiiarititj  of  boi  .x  is  r..qui- 
i:ie;  witn  ibme  powdered  ghii's,  by  which  t,,e  too  q.nc^ 
fbfioii  of  the  borax  is  retarded,  ana  the  precipitation, 
oftlie  earthy  matters  is  prevent^;.  If  rhc  ore  contains 
iron,  to  the  above  mixture  may  be  added  Ibme  alkaline 
fait. 

S  E  c  T.  VI  I.      Ores  of  Iron. 

J 

j§  2.  IRON  is  feldom  found  in  its  metallic  ftate,  and 

free  from  admixture  ;  though  Cramer  gives  an  accov.nt 

of  an  ore  which  needs  only  to  be  put  into  a  forge,  and 

heated  to  a  welding  heat.      Several  lands  and  earths 

alib  have  the  appearance  of  iron,  and  are  even  attract- 

able  by  a  magnet.     The  ore  mentioned  by  Cramer  is 

n:u::d  vitreried  :  with  moderate  blows  the  fcorias  are 

.1   ou.,  aild  :>  i\iafs  cf  iron  obtained,  which,  by 

beint^  put  into  the  fc.rge  :i^a:n,  ^'ves  tough  iron  with- 

But   in  genc!al  this  rnetal  is 

'  a  calx  ;   or,  though  it  is  combined 

v  of  the  principle  of  inflammability, 

it  baa  ieidcm  en^iigh  <.fJiQ  metallic  form  ;   and  it  is 

very  often  intermixed  vri:h  a  certain  proportion  offul- 

phur4.     Th_-  mi;.era  s  wrought  for  iron  are  three,  viz. 

iron  ore,  iron-iiore.  and  bog-fire. 

The  iron  ore  is  found  in  veins  as  the  ores  of  other 
metals  are,  and  the  appearance  is  very  various  ;  fome- 
tnrxs  it  has  a  rully  iron  colour  refembling  that  of  iron  ; 
fometimes  it  has  a  recldifli  caft :  often  it  is  formed  into 
a  fort  o£cryftaUizations  which  are  protuberant  knobs 
on  the  c u tiide  ;  and  the;'e  confift  of  fibres  tending  to  a 
common  centre,  a~.id  it  is  of  a  dark  colour  like  coagu- 
Jaied  blood.  It  is  called  h<n?m:i 'cs  or  bkod fom  ;  and 
ccnfiils  of  a  calx  cf  iron  with  a  fmall  quamity  of  vi 
triolic  acid. 

Iron 


3 

tron-ftone  in  Britain  is  clay  found  in  the  ftrata, 
xvirh  coal:  but  which  contains  a  large  quantity  of 
iron,  fo  as  to  make  the  working  profitable.  Some 
times  it  has  little  appearance  of  iron  ;  but  when  burnt 
with  a  certain  degree  of  heat,  it  becomes  of  a  deep 
red. 

The  bog-o'-e  is  an  ochre  of  iron,  and  is  found  gene 
rally  in  L..w  filiations,  and  in  fprings  containing  a 
fm*dl  quantity  of  iron,  w;  ich  flowing  over  thefe  grounds 
depoiits  it  in  the  form  of  ochre ;  and  after  a  number 
cf  ages  it  proves  a  rich  mine  of  iron,  and  it  is  extraft- 
ed  Irom  a  calx  of  this  kind  in  many  parts  of  the 
world.  There  is  3 lib  a  particular  kind  of  fpar  found 
in  different  com. trie*  of  a  pale  blue  colour,  fo  that 
fromi:s  firft  appearance  we  would  expecl  copper ;  but 
it  contains  a  fmall  quantity  of  iron,  and  is  a  combina 
tion  of  the  metal  \vith  inflammable  matter,  as  in  Pruf- 
fian  blue. 

The  load  ft  one  is  a  noted  iron  ore.  It  is  always 
found  in  veins,  and  it  is  a -lodged  that  it  is  only  pof- 
fefTed  of  its  magnetic  qualities  when  near  the  furface, 
In  appearance,  it  does  not  differ  from  rr  any  of  the  ores 
of  iron,  and  treated  as  an  ore,  it  affords  a  considerable 
quantity  of  metal. 

Neither  is  iron  generally  mincralifed  fo  diiiinctly 
as  other  metals  arc,  unlefs  in  pyrites  and  ores  of  other 
metals. 

Mod  cf  the  minerals  called  Iron  ores  have  an  earthy, 
rufty,  yellowifh,  or  brownift}  appearance,  which  pro 
ceeds  from  the  facility  with  which  the  true  iron  ores 
are  decompofed. 

Iron  is  the  moft  common  and  moft  abundant  cf  all 
metals.  In  Europe,  at  leaft,  we  cannot  find  an  eanh, 
a  fand,  a  chalk,  a  clay,  avitrifiable  or  calcinab'e  Hone, 
or  even  the  allies  of  any  fubilance,  which  do  net  con- 
lain  an  earth  convertible  into  iron.  All  earths  and 
ftor.es  which  arera  urally  yellow  or  red,  and  all  thofe 
which  acquire  thefe  colours  by  calcination,  receive 

them. 


them  from  the  ferruginous  earth  mixed  with  them. 
The  yellow  and  red  ochres  coniifl  aim  oil  iblely  of 
this  eanh  :  the  black  and  heavy  lands  are  generally 
very  ferruginous. 

The  iron  ore  mod  commonly  found  is  a  ilone  of 
the  colour  of  rail,  of  an  intermediate  weight  betwixt 
thefe  of  ores  in  general  and  unmetallic  ilones.  This, 
ore -has  no  determinate  iorm,  and  eaiily  furniftje's  an 
iron  of  goo.d  quality. 

Biocd-ltone  or  hematites,  fa^guine  or  rcd-cha.k, 
and  emery,  are  iron  ores  ;  iome  or  wbiehj  ior  inua^ce 
biccd-itone,  arc  aimed  all  imn.  Moil  of  thefe  lab-; 
fiances  require  but  a  flight  calcination  to  be  rendered 
very  attractable  by  a  magnet,  and  foluble  in  aqua 
fortis  ;  but  the  iron  obtained  form  them  is  of  a  ba  1 
quality,  and  they  are  therefore  neglected.  Iron  from 
the  hematites  is  very  brittle  ;  that  obtained  from  ochres  . 
is  red-inert.  All  thefe  iron  ores  are  fo  refractory,  that 
they  can  fcarcely  be  fu'e  '. 

Iron  ores  are  very  various  in  their  form  :  or  rather 
taey  have  no  determinate  form,  Sometimes  ti:.cy  are 
earth?,  fometimcs  icones,  fometimes  grains.  Accor- 
dtngly,  thole  naturaliils  who  attend  only  to  the  ex 
ternal  form  of  things  in  clafilng  and  fubdividing  mi 
nerals,  have  been  ob  iged  to  multiply  the  names  of 
iron  ores  ;  hence  they  are  called  irox  ores  in  f<:-r-n  of 
peafe,  cfbevis,  of  ccrtander  f.cds^  of  £cfip  r-corust  of  c  inn  a- 
<nc;;,  5:c.  which  Mr  Cramer  treats  as  iiiiculcus  trifies. 

§  2.  Grss  of  Ircn  viaj  be  eftiyed  by  the  following 
procefs : 

.  P  R.  O  C  E  S  S     I. 

[CRS.VF.R'S  Sirt  fff  •,  Proc.  54.] 

^o  reduce  a  precipitate  Iron  out  oflrs  ore  in  a  cjcfe  "Jfjjcf. 

".  ROAST  for  a  few  minutes  in  a  toft  under  a  muffle, 
and  with  a  pretty  iircng  fire,  two  centners  of  the 
iniall  weight  of  your  iron  ore  gioisly  pulverifed  ;  that 

the' 


r 

the  volatiles  may  be  ditfipated  in  part,  an  1  the  ore  it- 
felf  be  foftened  in  cafe  it  ihoald  be  too  hard.  When 
it  is  grown  cold,  beat  ir  extremely  fine,  and  roaft  it  a 
iecond  time,  as  you  do  the  copper-ore,  but  in  a  much 
ftronger  fire,  till  it  no  longer  emits  any  fmell ;  then  let 
it  grow  cold  again.  Compofe  a  flux  of  three  parts  of 
the  whits  flux,  with  ooe  part  off ufible  pulveri Ted  glafs, 
or  of  th-  like  ftertle  unfulphureous  fcorias,  and  add 
fandiver  and  coal-dud,  of  each  one-half  part  j  add  of 
this  flux  three  times  the  quantity  of  your  roafted  ore 
and  mix  the  whole  very  well  together ;  then  choofe  a 
very  good  crucible,  well  rubbed  with  lute  within,  to 
ftop  the  pores  that  may  be  here  and  there  unfeen  ;  put 
int»  it  the  ore  mixed  with  the  flux  ;  cover  it  over  with 
comm  m  filt ;  and  ffaut  it  clofe  with  a  tile,  and  with 
lute  applied  to  the  points. 

"  Put  the  wind-furnace  upon  its  bottom-part,  ha 
ving  a  bed  made  of  coal-daft.  Introduce  befides  into 
the  furnace  a  fmall  grate  fupported  on  its  iron  bars, 
and  a  ftone  upon  it,  whereon  the  crucible  may  ftand 
as  on  a  fupport :  furround  the  whole  with  hard  coals, 
not  very  large,  and  light  them  at  top.  When  the  veiTel 
begins  to  grow  red,  which  is  indicated  by  the  com 
mons  falt's  ceafing  to  crackle,  ftop  with  grofs  lute  the 
holes  of  the  bottom  part,  except  that  in  which  the 
ncz/le  of  the  bellows  is  received  :  blow  the  fire,  and 
excite  it  with  great  force,  adding  now  and  then  frefh 
fuel,  that  the  vcflel  may  be  never  naked  at  top  ;  ha 
ving  thus  continued  your  fire  in  its  full  ftrength  for 
three  quarters  of  an  hour,  or  for  a  whole  hour,  take 
next  the  velfel  out  of  it,  and  ftrike  feveral  times  the 
pavement  upon  which  it  is  fet,  that  the  fmall  grains 
of  iron  which  happen  to  be  difperfed  may  be  collected 
into  a  regulus,  which  you  will  find  after  having  broken 
the  veiTel. 

"  When  the  regulus  is  weighed,  try  its  malleabi 
lity  :  then  make  it  reel-hot ;  and  when  fo,  ftrike  it 
with  a  hammer  :  if  it  bears  the  ftrokes  of  a  hammer, 
both  when  red  hot  and  when  cold,  and  extends  a  little, 

you 


[    429     3 

you  may  pronounce  your  iron  very  good  ;  but  if,  when 
either  hot  or  cold,  it  proves  brittle,  you  may  judge  it 
to  be  not  quite  pure,  but  (till  in  a  femi-mincrai  con 
dition. 

"  Remarks.  The  arfenic,  but  efpecially  the  fulphur 
mu ft  be  diffipated  by  reading  :  for  the  former  renders 
the  iron  brittle  ;  and  the  latter  not  only  does  the  fim.e, 
but,  being  managed  in  a  clcfe  veflel,  with  a  falirie  al 
kaline  flux,  turns  to  a  liver  of  fulphur  ;  to  the  action 
of  which  iron  yielding  in  every  refpect,  it  can  upon 
no  account  be  precipitated,  and  if  not  the  \\hole,  a 
gre  it  part  of  it  at  leaft  is  retained  by  the  fulphureous 
fcoria ;  fo  that  in  this  cafe  you  commonly  in  vain  look 
for  a  regulus. 

"  The  iron  obtain-  d  from  this  f.rft  precipitation 
has  h.-rdly  ever  the  requilite  ductility,  but  is  rat1  er 
brittle ;  the  reaibn  o-'  which  is,  that  the  fulphur  and 
arfenic  remains  in  it ;  for  notwithstanding  that  the 
greateil  part  of  thefe  is  diiTJp  itc-d  by  roafting,  yet 
ilme  part  adheres  fo  ilricViy,  that  it  can  never  be  fe* 
paratcd  but  with  absorbent,  terreftrial,  alkaline  ingre 
dients,  that  change  the  nature  of  the  fulphur.  For 
which  reafon,  in  larger  operations,  they  add  quick 
lime,  or  marble  ftones  that  turn  into  quicklime ; 
which,  while  they  abfbrh  the  faid  minerals,  are,  by  it 
and  by  help  of  the  deftroyed  part  of  the  iron,  brought 
to  a  fufion,  and  turn  to  a  vitrified  fcoria  ;  although,  at 
other  times,  they  refill  fo  much  by  their  own  nature  a 
vitrification-  Another  caufc  of  the  brittlcnefs  of  iron 
is  the  unmetaliic  e.'.rth,  when  it  is  not  yet  feparated 
from  it ;  for  the  iron  ere  contains  a  great  quantity  of 
it,  and  in  the  melting  remains  joined  with  the  reguline 
p.irt  :  whence  the  iron  is  rendered  very  coarie  and 
brittle.  Some  iron  ores  are  altogether  untractable : 
ncverthelefs,  the  regulu.fes  produced  out  cf  them,  when 
broken, have  fometimcs  a  reatfemimetallic  look;  which 
proceeds  undoubtedly  from  a  mixture  of  a  fm all  quan 
tity  of  ibme  other  metal  or  femimetal." 

P  P.  O- 


[     430     ] 

PROCESS      II. 

[[The  following  Procefs  for  eflaying  iron  ores,  and 
ferruginous  itones  and  earths,  is  extracted  from 
MrGcUert's  Efem.-nts  of  cjjaymg.'} 

"  ROAST  two  quintals  of  iron  ore,  or  of  ferrugi 
nous  ear.h  :  divide  the  rcafted  matter  into  two  equal 
parts:  to  each  of  which  add  half  a  quintal  of  puive- 
rifed  glafs,  if  the  fubftance  be  fufiblc  and  contain- 
.much  metal;  but  if  otherwiie,  acid  ah'o  half  a  quintal 
of  calcined  borax.  If  the  reading*  has  entirely  difen- 
gagcd  the  fulphur  and  ;;iienic,  an  eiglith  r  art,  or  even 
half  a  quintal,  of  quick] ime  may  be  added.  VviJi  the 
above  matters  mix  twelve  pounds  of  charcoal  powder. 

"  Take  a  crucible,  and  cover  the  bottom  and  licks 
r"  its  inner  iurfuce  with  a  pafte  made  oi  three  parts 
o  charco;;l-duft  and  one  part  of  clay  bor.t  U  Aether. 
In  the  hollow  left,  in  this  paite  put  the  above  mixture  ; 
prefs  it  lightly  clown  ;  cover  i::  with  puivcriied  glafs  ; 
and  put  on  the  lid  of  the  crucible, 

"  Place  two  fuch  crucibles  at  the  diftance  of  about 
four  fingers  from  the  air-pipe,  in  fuch  a  manner  that 
the  air  ihall  pafs  betwixt  them  at  about  the  third  part 
of  the  height  from  the  bottcm  ;  fill  the  ibace  be 
twixt  the  two  crucibles  with  coals  of  a  moderate  rl/:e  : 
throw  lighted  coals  upon  them,  that  the  fire  n,ay  clc- 
fccnd  and  make  them  red-hot  from  top  to  botroni ;  lit 
tirft  let  the  bellows  blov/foftly,  and  afterwai'd:-.  ftiongly 
during  an  hour,  or  anhcur  and  a  quarter:  then  t^Vo 
away  the  crucible,  and  break  it  when  cold.  A  regulir^ 
will  be  found  in  the  bottcm,  and  fometimes  feme  irr.all 
grains  of  iron  in  die  fcoria,  which  muit  be  ieri.ratcd 
and  weighed  along  with  the  regulus  :  thin  try  the 
regulus  whether  it  can  be  extended  under  the  hammer 
when  hot  and  when  cold. 

"  Remarks.  To  disengage  a  metal  frcrn  the  ear'hy 
matters  mixed  with  it  by  fire,  \ve  mud  chai:gc  t]-e,'e 

.matters 


L     43>      3 

in.itters  into  fcoria  or  glafs.  This  change  may  be 
effected  by  adding  feme  iubdance  capable  of  diflblving 
thefe  matters  ;  that  is,  of  converting  them  into  a  fcoria 
or  glafs,  from  which  the  metallic  matters  may,  by 
their  weight,  feparate  and  form  a  regulus  lit  bottom. 
Fixed  alkali,  which  is  an  ingredient  of  the  black  and 
of  the  \\hite  flux,  is  a  powerful  folvent  of  earths  and 
ftones  ;  but  the  alkali  does  alfo  diiiblve  iron,  efpecially 
when  this  is  in  a  calcined  or  earthy  flate  ;  and  this 
folution  is  fo  much  more  complete,  as  the  hre  is  longer 
applied.  Hence,  in  ordinary  ell  ays,  where  an  alkaline 
,lalt  is  ufed,  little  or  no  regulus  of  iron  is  obtained. 
Now,  glafs  acts  upon  and  diilblves  earths  and  ftones  ; 
but  not,  or  very  little,  iron  :  confcquently  glafs  ib  the 
bed  flux  for  fuch  eilays,  and  experience  confirms  this 
affci tion.  If  the  ore  contains  but  little  iron  we  may 
alfo  add  to  the  glafs  fome  borax  ;  but  borax  cannot 
be  employed  fmgly,  becaufe  it  very  foon  fufes  and  fe- 
parates  from  the  ore  before  the  metal  is  revived.  Quick 
lime  is  added,  not  only  to  abforb  the  fulphur  and  arfe- 
nic  remaining  in  the  ore,  but  alfo  becaufe  it  diilblves 
and  vitrifies  the  ftony  and  earthy  matters  of  iron  ores 
which  are  generally  argillaceous.  For  which  reafon, 
in  the  large  operations  tor  fmelting  iron  ore,  quicklime, 
and  even  in  certain  cafes  gvpfuin,  are  commonly  added 
to  facilitate  the  fufion. 

"  The  reduction  of  iron-ore,  and  even  the  foilon  of 
iron,  requires  a  violent  and  long-contkiued  heat ; 
therefore  in  this  operation,  we  muit  not  employ  an 
inflammable  fubflavjce,  as  pitch,  that  is  icon  confu- 
med,  but  charcoal  pulverifed,  which  in  clofe  veifels  is 
notfeniibly  wafted.  Too  much  charcoal  mull  not  be 
added,  elfe  it  will  prevent  the  action  of  the  glafs  upon 
the  earthy  matter  of  the  ore,  and  coniequently  the 
ieparation  of  the  'metallic  pait.  Experiments  have 
taught  me,  that  one  part  of  charcoal  dull  to  eight 
parts  ot  ore  was  the  bed  proportion. 

N  n  l  «  Whe» 


C     43*     3 

"  When  iron  is  furrounded  by  charcoal,  it  is  not  de- 
^ompoied  or  deftroyed  ;  hence  the  iron  of  the  ore, 
which  finks  into  the  hollow  made  of  paile  of  charcoal, 
tluit  and  clay,  remains  there  unhurt.  The  clay  rs 
-added  in  this  pafte  to  render  it  more  compact,  and  to 
keep  the  fluid  iron  collected  together. 

"  The  air  is  directed  betwixt  the  crucibles ;  becaufe 
if  it  was  thrown  directly  upon  them,  they  would 
fcarcely  be  able  to  relift  the  heat.  The  fpace  betwixt 
the  air-pipe  and  the  crucibles  ought  to  be  conftantly 
niled  with  charcoal,  to  prevent  the  cold  air  from 
•touching  the  crucibles.  Ductile  and  malleable  iron  is 
ieldom  obtained  in  this  firil  operation.  The  fulphur 
and  arfenic,  and  frequently  al:'b  an  earthy  matter  adhe 
ring  to  the  iron,  prevent  thefe  qualities." 

SECT.  VIIT.     Ores  of  Mercury. 

y.  i.  MERCURY  is  fometimes  found  pure,  fluid,  and 
in  its  proper  metallic  itatc,  only  mixed  with  earths 
•*md  flones.  Such  are  the  ores  of  mejcury  found  near 
Montpelier,  in  Tuicany,  and  in  other  places. 

But  the  largeft  quantity  of  the  mercury  found  in 
the  earth  is  mineralifed  by  fulphur,  and  confequently 
is  in  the  form  ot  cinnabar. 

Mercury  is  never  mine:  alifed  by  arfenic.  The  richeii 
mine  of  mercury  is  that  ot  Almadin,  in  Spain. 

Linnsus  and  Cronftedt  mention  a  fingular  ore,  in 
which  the  mercury  is  mi.ieralifi-d  ly  fulphur  and  by  cop 
per.  It  is  laid  to  be  of  a  blackilh-grey  colour,  of  a 
glaffy  texture,  and  brittle.  When  the  mercury  and 
iulphur  arc  expelled  by  fire,  the  copper  is  diibovered 
by  giving  an  opake  red  colour  to  glafs  of  borax. 
which,  by  continuance  and  increafe  of  heat,  becomes 
green  and  tranfparent. 

§  2.  Cramer  directs,  that  ores  of  mercury  Jhould  Is 
ejaycd  by  tlie  following  procefies  : 

PRO- 


C    433     J 

PROCESS     I. 

To  ftparaie  mercury    out  of  an    unfuipktireoit;    ore    ly 


*'  TAKE  a  lump  of  the  pulverifed  ore,  one  common 
pound,  which  mult  (land  for  one  centner  :  put  it  into 
a  glafs  retort  perfectly  clean,  well  loricated,  or  coat 
ed  up  to  half  the  length  of  its  neck,  this  muft  be  very 
long,  and  turned  backwards  with  fuch  a  declivity, 
that  a  glafs  recipient  may  be  perpendicularly  applied 
to  it  :  but  you  muft  choefe  a  retort  fmall  enough,  that 
the  belly  of  it  may  be  filled  hardly  two-thirds  with  the 
ore  :  this  retort  muft  be  placed  fo,  that  nothing  of  the 
fluid  adherent  to  the  neck  of  it  may  fall  in  the  ca 
vity  of  the  belly,  but  that  the  whole  may  run  forward 
into  the  recipient.  Finally,  have  a  fmall  recipient 
full  of  cold  water  :  let  it  be  perpendicularly  fituated, 
and  receive  the  neck  of  the  retort  in  fuch  manner  that 
the  extremity  of  it  be  hardly  one  half-inch  immerfed 
into  the  water. 

"  Let  the  retort  be  furrounded  with  hot  burning 
coals  placed  at  forne  diftanee  in  form  of  a  circle,  left 
the  veflel  ihould  burft  by  too  fudden  a  heat  :  then  by 
degrees  bring  the  burning  coals  nearer  and  nearer,  and 
at  iaft  furround  the  whole  retort  with  them  and  with 
frelh  charcoal,  that  it  may  grow  fiightly  red-hot  ;  this 
fire  having  been  continued  for  an  hour,  let  the  retort 
cool  of  itlelf  :  then  ftrike  the  neck  of  it  gently,  that 
the  large  drops  which  are  always  adherent  to  it  may 
fall  into  the  recipient  :  let  the  recipient  be  taken  away 
and  the  water  feparated  from  the  mercury  by  filtra- 
tion,  and  let  the  mercury  be  weighed.  This  opera 
tion  may  be  more  conveniently  performed  in  a  land- 
bath  ;  in  which  cafe  the  pot  containing  the  fand  muft 
be  middling  red-hot,  and  the  retort  be  able  to  touch 
the  bottom  of  it  immediately  ;  nor  is  it  then  neceflary 
that  the  retort  be  loricated." 

N  n  2  PRO- 


[     434     ] 

PROCESS     II. 

To  revhe  mercury  from  a fulpkureous  c'tnnalar-orc. 

"  BEAT  your  ore  extremely  fine,  and  mix  it  ex'a<51'- 
ly  with  an  equal  portion  of  iron-filings,  not  rully  ; 
proceed  to  dillil  it  with  the  fume  apparatus  as  in 
the  former  procefs,  but  urge  it  with  die ,  ftrcngeft 
fire  that  can  be  made.  .  .  :.  •  • 

"Cinnabar  may  be  feparated  from  (tones  by.fub- 
limation  thus :  Beat  it  to  a  fine  powder,  and  put  k 
into  a  fmall  narrow  glafs  or  earthen  cucurbit,  the 
belly  of  which  it  mud  not  fill  more  than  one-third 
part:  ftop  the  orifice  at  top;  this  muft  be  very  nar 
row,  to  hinder  the  free  aclion  of  the  air.  Put  this 
fmali  cucurbit  in  an  earthen  pot  above  two  inches  wide 
in  diameter,  and  gather  fand  around  this  pot  about  as 
high  as  the  pulverifed  ore  rifes  in  the  cucurbit.  Then 
put  it  upon  -burning  coals  in  fuch  manner  that  the  bot 
tom  of  the  pot  may  be  middling  red-hot.  Thus  will  your 
cinnabar  afcend  and  form  a  folid  ponderous  ring,  which 
irmft  be  got  out  by  breaking  the  vefFel. 

SECT.  IX.     Ore  tf  ike  Regains  of  Antimony. 

NATIVE  regulus  of  antimony  was  firft  obferved  by 
Mr  Swab,  in  Sweden,  in  the  mine  of  Salberg,  and 
defcribcd  by  him  in  the  memoirs  of  the  Swediili  Aca 
demy  in  1749.  Mr  Wallerius  mentions  it  in  his  JMi- 
neralogy. 

Regulus,  of  antimony  is  generally  united  with  ful- 
phur,  with  which  it  forms  antimony,  which  ought  -to 
be  confidercd  as  a  true  oie  of  .the  regulus  oi  ami- 
niony. 

Another  ore  of  regulus  -of  antimony  is  alfo  known 
of  a  red  colour,  in  which  'the  regulus  is  male  rallied 
both  by  arfenic  and  by  fulphiu.  ri  his  ore  reiemhlc*; 
icme  iron  ores;  and  feme  kind  cf  blciul.  it  is  di- 

itinguiilicd 


C     435     ] 

ftinguifhed  by  its  great  fufibility,  which  is  fuch,  that 
it  may  be  eafily  melted  by  the  flame  of  a  candle. 

The  native  regains  of  antimony,  by  Von  Swab,  is 
raid  by  that  author  to  have  differed  from  the  regulus 
of  antimony  obtained  from  ores,  in  thefe  two  proper 
ties,  that  it  was  capable  of  being  eafily  amalgamated 
Y7<th  mercury,  and  that  its  calx  Ihot  into  cryftals  during 
the  cooling. 

Befides  the  ores  of  regulus  of  antimony  enumerated 
above,  this  femimetal  is  alfo  found  in  ores  of  other 
metallic  fubftances,  as  in  the  plumofejilver-ore,  and  in 
the  ftibiated  lead-ore. 

§  2.  The  ores  of  antimony  may  be  effayad  by  the  fol 
lowing  proceffes  defcribed  by  Mr  Cramer. 

PROCESS     I. 

70  obtain  antimony  from  ils  ore. 

**  CHOOSE  a  melting  crucible,  or  an  earthen  pot  not 
glazed,  th;>  may  contain  ibme  common  pounds  of 
the  ore  of  antimony,  broken  into  fmall  bits.  Bore  at. 
the  bottom  of  the  crucible  fome  fmall  holes,  two  lines 
in  diameter.  Let  the  bottom  of  the  vdlel  be  recei 
ved  by  the  orifice  01  a  fmaller  one,  upon  which  it  muft 
be  put ;  and  when  the  ore  is  put  into  it,  let  it  be 
covered  with  a  tile,  and  all  the  joints  be  flopped  with 
lute. 

«*  Put  thefe  vefl'els  upon  the  pavement  of  a  hearth 
and  put  ftones  all  round  them  at  the  diftance  of  fix 
inches.  Fill  this  intermediate  fpace  with  afhes,  fo 
high  that  the  inferior  pot  be  covered  to  the  upper 
brim.  Then  put  frefh  and  burning  ccals  upon  it, 
and  with  a  pair  of  hand-bellows  excite  the  fire,  till 
the  upper  veffel*  grow  red-hot:  take  off  the  fire  a 
quarter  of  an  hour  after ;  and  when  the  veffels  are 
grown  coldj  open  them.  Yob  will  find  that  the 
N  n  3  xneltecji 


E    43«    3 

mesed  ~nt>mony  has  run  through  the  holes  mad?  nt 
the  bottom  of  the  upper  veiiei  into  the  inferior  oae, 
wkere  it  is  collected." 


PROCESS      II. 

'To  roafl  crude,  antiinGny%  or  iff   «//v,  with  or  witfaut  ad 
dition. 

"CHOOSE  an  earthen,  fiat,  low  difli,  not  glazed} 
and  if  it  cannot  bear  being  made  middling  red  hot  ; 
cover  it  over  with  a  coat  of  lute  without.     Spread  it 
thinly  over  with  crude  antimony,  or  with  its  ore,  bea 
ten   to  a  pretty    caarfe  powder,  not  exceeding  a  few 
ounces  at  once.     Put  the  ciifh  upon  a  fire-p  in,  having 
a  few  burning  coals  in  it :  increafe  the  fire  till  it  begins 
to  fmoke  a  little.  Meanvrhile  you  mtift  mcefianiily  move 
the  powder  with  a    piece    of  new  tobacco-pipe  ;  for 
this  caufes  the  fulphur  to  evapotv.te  the  fooner.  If  you 
increafe  the  fire  a  little  too  foon,  the  powder  imme 
diately  gathers  into  large  clots,  or  even  begins  to  melt. 
When   this   happens,  take  it  immediately  <-S  the  fire 
before  it  melts  entirely.    Then  pulverife  it  again,  and 
finally,    make    a    gentle    fire  under  it.     Your  black 
ihining  powder  will  ailume  an  alii  colour  almoft  like 
that  of  earth,  and  become  more  refra&ory  in  the  fire  ; 
wherefore  you  may  then  increafe  the  fire    till  .your 
powder  grows  middling  red-hot,  and  let  it  lad  till  it- 
ceafes  to  fmoke.     If  you  add  to  your  crude  antimony 
pulverifed,  half  or  an  equal  quantity  of  charcoal-daft, 
and  perform  the  reft  as  above,  die  rcafting  will  be 
done  more  conveniently  :    for  it  dc  es  not  gather  10 
eafily  into  clots,  and  melts  with  much  greater  difficul 
ty.   When  part  of  die  fulphur  is  evaporated,  add  ibrne 
fat  to  it  at  feveral  times.    Thus  you  will  fooner  finiflr 
the  operation,  and  the  remaining  calx  will  not  be  burnt 
to  excefs.     However,  if  it  be  thus  expofed  to  too  vio-, 
kntand  long-lafting  a  fire,  a  great  quantity  of  it  eva 
porates  ; 


C     437     1 

poratss-,  nor  does  k  ce;iie  entirely  to  frnokc  in  a  jrrcat' 
tire.     And  ic  will  he  enough,  if,  growing  middling 
red-hot,  it  does  no  longer  emit  the  unpleaiant  fineil  ot  • 
the  acid  of  fulphur." 

P  R  O  C  E  S,  S     III. 

To  reduce  a  calx  of  atttlmany  into  a  f.mimitL.lic  rcgxks. 

"  Mix  fome  calx  of  antimony  w'th  a  quarter  part 
of  the  black  flax,  which  put  into  the  crucible.  Cover 
the  vellel  with  a  tile  ;  make  the  fire  as  quickly  as  the 
veiiel  can  hear  it,  hue  no  greater  than  is  nece'fury  to 
melt  the  flux.  When  the  whole  has  been  well  in  fufiOn 
for  half  a  quarter  cf  an  hour  (which  may  be  tried 
with  a  tobacco-pipe,  taking'  off  the  tile),  pour  it  into 
the  melting  cone,  which  mufi  be  warm  and  done  over 
with  tallow.  Then  immediately  ftrike  the  cone  feve- 
ral  times.  You  will  find,  when  the  cone  is  inverted,  a 
regulus,  above  which  is  a  (aline  fcoria," 

The  methods  of  cclcinirg  antimcnyly  means  of  nitre  r 
arc  described  under  CHEMISTRY,  ne  1252 — 1265  5  ant^" 
thole  of  obcaining  a  regiiltis  of  antimony  without  a  pre^. 
vious  calci nation  or  roaiting,  by  throwing  a  mixture  of 
powdered  antimony,  tartar,  and  nitre,  into  a  red-hot 
crucible,  and  by  fufrag  this  mixture,  and  of  obtaining 
a  martial  regu'uts  of  antimony •>  are  defcribed  at  the  ar 
ticle  REGULUS. 

SECT.     X.     Ores  of  Bifmuth. 

§.  i.  BISMUTH  is  found  native^  refcinbling  the  re 
gulus  of  bifmuth. 

An  cfhre  cf  bi  muth,  of  a  whitifh  yellow  colour,  is 
wien-ticned  by  Cronftedt ;  and  is  different  from  '»he 
ore  imprope-ly  called  powers  of  I  if  muth,  which  is  a 
calx  of  cobalt. 

Bifmutli  is  xnineralifed  x.  By  fulplmr.  This  ore 

has 


C   43*    ] 

lias  the  appearance  of  galena.  2.  With  futykurated 
iron.  Bifmuth  is  found  alfo  in  cobalts,  and  in  fomc 
ores  of  fiher. 

§  2.  Ores  of  b':fmutb  may  be  efayed  by  the  follow 
ing  procefs. 

"  Bifmuth  ore  may  be  melted  with  the  fame  ap 
paratus  as  was  directed  for  the  fufion  of  crude  anti 
mony  out  of  its  ore.  Or  you  may  beat  your  ore  to  a 
very  fine  powder,  with  the  black  flux,  fandiver,  and 
common  fait,  in  a  clofe  veffel,  like  the  ore  of  lead  or 
of  tin,  and  melt  it  in  a  middling  fire,  having  a  draught 
of  air.  But  as  this  femimetal  is  dcftru&ible  and  vo 
latile,  you  muft  as  quick  as  poffible  apply  to  it  that 
degree  of  fire,  which  the  flux  requires  to  be  melted; 
and  fo  foon  as  it  is  well  melted,  the  veifol  muft  be  ta 
ken  out  of  the  fire  ;  and  when  it  is  grown  quite  cold 
and  broken,  you  will  find  your  regulus." 

Mr  Gellert  directs  that  ores  of  biimuth  fliould  be 
effcyed  by  fufmga  quintal  of  pulverifed  ore  with  half 
a  quintal  of  calcined  borax,  and  half  a  quintal  of  pul- 
vcrifed  glafs,  in  order  to  vitrify  the  adherent  earths 
and  ftones  which  envelope  the  bifmuth.  But  probably 
the  heat  reqviifite  for  this  vitrification  would  volatilife 
part  of  the  bifmuth. 

If  the  ore  be  of  the  kinds  above  defcribed,  minera- 
lifed  by  fulphur,  or  by  fulphur  and  iron,  a  previous 
roafting  would  be  expedient,  which  may  be  performed 
in  the  fame  manner  as  is  directed  for  the  roafting 
of  kiitimony. 

SECT.  XI.     Ores  of  the  Regulus  ofColalt. 

COBALT  is  a  grey -coloured  mineral,  with  more  or 
lefs  of  a  metallic  appearance.  Its  grain  is  clofe  ;  it  is 
compact  and  heavy,  and  frequently  covered  with  ,an 
efflorefcer.ee  of  peach-coloured  flowers.  Of  this  feve^ 
ral  kinds  are  known.  All  the  true  cobalts  contain  the 

femimetaJ 


C     439     ]: 

femimctal  called  regulus  of  cobalt,  the  calx  of  which 
becomes  blue  by  vitrification;-    This-  regulas  is'  mine-  - 
rallied  in  cobalt  by  fulphur, 'and-  efpeciaily  by  a  large- 
quantity  of  arienic.      Some  cobalts  alib  contain  bif- 
muth  and  filver. 

Audiors  -have  given  the  name  of  cobalt  to  many  mi 
nerals,  although  they  do  not  contain  the  femimctal 
ubovementioned,-  but  only  becaufe  they  externally  re- 
i£mble:therore  of  the  regulus  of  cobalt.  But  thefe 
minerals  can  only  be  coniixlered  as  falfc  cobalts.  They 
are  diftin-gir.ihable  from  true  cobalt  by  trying  whe 
ther  they  can  yield  the  blue  glafs  calledywra//,  and  the. 
iympathetic  ink.  The  red  efTiorefcence  is  alfo  a> 
mark  by  which  true  cobalt  is  diftinguifhabk  from  the, 
falfe  :  'but  this  efflorefcence  only  happens  when  the  ore 
has  been  expofed  to  a  moift  ai*. 

The  principal  m  hies  of -cobalt  are  in  Saxony,  where, 
they  are  dug  ibr  the  fake  of  obtaining  zaffre,-a55ivrerf 
blue  or  frnalt,  and  arfenic.  Very  fine  cobalt  is  alfa 
found  in  the  Pyrenean  mountains.  It  has  been. like- 
wife  found  in  Ccn-nwall  and  Scotland.  And  that  it  ife 
in  the  eaftern  parts  of  Afia,  appears  from  the  blue  co*. 
louring  on  old  oriental  porcelain:  but  probably  die 
mines  difcorered  in  thefe  -countries  are  nearly  exhauft- 
ed,  as  contid'erable. quantities-  of  zafire  and-imalt  are: 
exported  from  Europe  to  China,  i 

Cobalt  is  heavier  than  moil  other  ores,  from  the 
large  quantity  of  arfenic  it  contains ;  and-. in  this  re-' 
fipcct-  it  refembles  the.  ore  of  tin. 

Befides  the  grey  -or.  afh -coloured  cobalt  above  de-. 
fcribed,  which  is  the  moft  frequent,  other  .cobalts-  are. 
found  of  various  colours  and  textures,  mixed  with  va 
rious  fubfVanees.  .Waller ius.  enumerates  fix  fpecies  of 
cobalts.  I .  The  "afl7-c6l'.'iirc(l  ore,  which  is  regulus  of 
cobalt  mineniliicd  by  ari-cnic,  coftfvfting  of  lliining 
ienderucoioureJ  .grains*  Some  ores  of  this  kind -are; 
compact  refemblmg  itcel,  and  others  arc  ^f  a  loofe 
lexturc-  and  friable.  2.  The/£  cu/ar  ore  isblack,  lliining 

like 


[     440     ] 

Hke  a  mirror,  and  laminated.  This  fpecies  is  very 
rare  ;  and  is  fuppofed  by  Wallerius  to  be  a  foliated 
ipar,  or  felenites  mixed  with  cobalt,  3.  The  vitreous 
vrjtag-tike  orv,  is  of  abluiih,  (liming  colour,  compact, 
or  fpongy.  4.  CiyJlaJlized  ore,  is  a  grey,  deep-colour- 
ed  cobalt,  confiding  ofclufters  of  cubical,  pyramidal, 
prifmatic  cryftals.  5.  Flowers  of  cobalt,  red,  yellow, 
or  violet.  Thefe  flowers  feem  to  be  formed  from  fome 
of  the  above-defcribed  compact  ores,  decompofed  by 
cxpofure  to  moid  air.  This  decompofition  is  fimilar 
to  that  which  happens  to  ferruginous  and  cupreous  py 
rites.  6.  The  earthy  colah  is  of  a  greenijh  white,  or 
of  a  yellow  colour,  and  of  a  foft  and  friable  texture. 
This  fpecies  feems  to  be  an  ochre  of  cobalt  ;  and  is 
formed  .perhaps  from  the  flowers  of  cobalt  further  de 
compofed,  in  the  fame  manner  as  a  martial  ochre  is 
iormed  from  the  faline  efflorefcence  of  decompofmg 
pyrites  ;  when  this  efflorefcence  is  further  decompo- 
fed  by  expofure  to  moift  air  ;  by  which  the  vitrio 
lic  acid  contained  in  it  is  expelled,  and  the  effloref- 
cence  is  changed  from  a  faline  ftate  to  that  ot  an 
ochre  or  calx. 

Befides  thefe  proper  ores,  cobalt  is  alfo  found  in 
a  blue  clay  along  with  native  filver,  in  ores  of  bif- 
iButh,  and  in  the  mineral  called  lupfernrteL  See 
NICKEL. 

The  effay  of  cobalt  is  defcribedat  the  article  REGW- 
ofCola/t. 


SECT.  XII.     OretofZinr. 

§  I.  THE  proper  ore  of  z,inc  is  a  fubftance  which  has 
rather  an  earthy  or  ftony  than  metallic  appearance,  and 
is  called  caJawy,  calamlne,  or  lapis  caiim'maris.  This 
ilone,  although  metallic,  is  but  moderately  heavy,  and 
has  not  the  brilliancy  of  moll  other  ores.  Its  colour 
is  yellow,  and  like  that  of  ruih  It  is  alfo  lefs  denfc. 
than  other  metallic  minerals.  It  feems  to  be  an  ore 

naturally 


C     44'     3 

naturally  dccompofed.  The  calamine  is  not  work 
ed  direclly  to  obtain  zinc  from  it,  becaufe  this 
would  only  fucceed  in  clofe  velfels,  and  coniequent- 
ly  with  fmall  quantities,  according  to  Mr  Margraaf's 
procefs.  But  it  is  fuccefsfully  employed  for  the  con- 
verlion  of  copper  into  bra^s  by  cementation,  by  which 
the  exigence  of  zinc  in  that  ftone  is  fufficiently 
proved. 

Mr  Wallerius  enumerates  ulfo  amonglt  the  ores  of 
/.inc  a  very  compounded  mineral,  confiding  of  zinc, 
fulphur,  iron,  and  arfenic.  This  mineral,  called  blend> 
refembles  externally  the  ore  of  lead,  and  hence  has 
been  called  fa /fe  ga/;na.  Thefe  blends  have  different 
forms  and  colours  ;  but  are  chiefly  red,  like  the  red  ore 
of  antimony. 

Zinc  is  obtained  from  certain  minerals  in  the  Eaft 
Indies,  of  which  we  know  little. 

Calciform  ores  of  zinc,  according  to  Cronftedt,  are 
pure  or  mixed.  The  pure  are  indurated,  and  ibme- 
times  cryitallized,  refembling  lead-fpar.  The  mixed 
ore  contains  alfo  fome  calx  of  iron.  This  is  cala;nine. 
It  is  whitilh,  yellowiih,  reddifn,  or  brown. 

Zinc  is  minerattfed,  l.  ~&y  ftilphuraied  iron.  Ort  of 
~.itic.  Wallerius  lays,  lead  is  fometimes  contained  in 
th's  ore.  It  is  white,  blue,  or  brown.  2.  ByyW- 
phur,  arfenicy  and  iron.  Blend,  or  pfsudo-galena,  or 
faife-gakna,  or  black-jack.  Thefe  art  of  various  co 
lours,  white  yellowiili,  brown,  reddifh,  greeniih, 
black.  They  coniift  of  fcales,  or  are  teifelateld.  Mr 
Cronftedt  thinks,  that  in  the  blends  the  zinc  is  minerali- 
ied  in  the  Hate  of  a  calx,  and  in  the  ore  of  zinc  in  its 
metallic  fta*e.  ' 

§  2.  Although  the  minerals  above  enumerated  have 
been  known,  from  their  property  of  .converting  copper 
into  brafs,  to  be  ores  of  zinc,  yet  the  method  of  ef- 
faying  them  fo  as  to  obtain  the  contained  zinc  was  not 
known,  or  at  lead  not  pubiiilied,  bofore  Mr  MargraaPs 
Memoir  of  the  Berlin  Academy  for  the  year  1 746, 

upon 


[     44'     ] 

upon  that  fubject.  That  very  able  chcmift  has  fhown, 
>that  zinc  may  be  obtained  from  its  ores,  from  the 
fiowers,  or  fiom  any  other  calx  of  zinc,  by  treating 
thefe  with  charcoal-dull,  in  clofe  veiiels,  to  prevent 
the  ccmbufhon  of  the  zinc,  which  happens  immediate 
ly  upon  its  reduction  when  expofed  to  air.  For  this 
purpofe,  he  put  a  quantity  cf  finely  powdered  ca- 
lamme,  or  roaited  Ulend,  or  other  calx  of  zinc,  well 
mixed  with  an  eighth  part  cf  charcoal-duft,  into  a 
ftrong,  luted  earthen  retort,  to  which  he  fitted  a  recei 
ver.  Having  placed  his  retort  in  a  furnace  and  rsifcd 
the  fire,  he  applied  a  violent  heat  during  two  hours. 
When  the  veflels  were  cold  and  broken,  he  found  the 
zinc  in  its  metallic  form  adhering  to  the  neck  of  the 
retort. 

.  The  chief  difficulty  in  this  operation  is  to  get  an 
earthen  retort  fufficiently  compact  to  retain  the  va 
pour  of  the  zinc  (for  it  eafily  pervades  the  Heffinn 
crucibles.  Stourbrldge  melting  pots,  and  fimilar  vef- 
fels,  as  may  be  ieen  from  the  quantity  of  fiowers 
which  appear  upon  their  cuter  furface,  when  zinc  or 
it:;  calxes  and  any  inflammable  i::- a  tier  have  been  ex 
pofed  to  heat  within  thefe  veffcls),  and  at  the  fame 
tm»e  -efficiently  ftrong  to  refill  the  violent  fire  which 
Mr  Margraaf  requires. 

A  i  •  <;-ty  exact  eiiay  cf  an  ore  of  zinc  may  be  made 
in  the  fallowing  manner. 

Mix  a  quantity  of  pulverifed  roafled  ore  or  calx  of  zinc 
n  eighth  part  of  charcoal-duft.  Put  this  mixture 
K  ft  crucible  capable  of  containing  thrice  ;.he  quan- 
titj  Diil  life  equally  amongft  this  mixture  a  quantity 
ol  'm-  11  grahv  or  tliin  plates  of  copper  equal  to  that  of 
tLecalamine  or  ore  employed,  and  npon  tlie  wliole  J<iy 
another  equal  quantity  of  grains  or  plates  of  copper  ; 
and  laftly,  cover  tjiis  latter  portion  cf  copper  with 
charcoal-duft.  Lute  a  lid  upon  the  crucible,  and  ap 
ply  a  red  heat  during  an  hour  or  two.  The  copper  or 
part  of  it  will  unite  with  the  vapour  of  the  zinc,  and 
2  be 


[  -  443     J 

he  thereby  converted  into  brafs.  By  comparing  the 
weight  of  all  the  metal  alter  the  operation-  with  the 
weight  of  the  copper  employed,  the  weight  acquired, 
and  consequently  the  quantity  of  y,inc  unired  with  the 
copper  will  be  known.  The  copper  which  has  not 
been  converted  inio  hrafs,  or  more  copper  whh •freih 
charcoal-duft,  may  be  again  added  in  the  fame  man 
ner  to  the  remaining  ore,  and  the  operation  repeated 
with  a  heat  fornewhat  more  intenfe,  that  any  zinc  re 
maining  in  the  ore  may  be  thus  extracted.  A  curious 
circumftance  is,  that  a  much  greater  heat  is  required 
to  obtain  /inc  from  its  ore  by  dirt  illation,  than  in  the 
operation  now  defcribed  of  making  brais  ;  in  which 
the  feparaticn  of  the  zinc  from  its  ore  feerns  to  be  fa 
cilitated  by  its  dilpo.ition  to  unite  with  copper. 

SECT.   IV.      Ores   cf  slrjl-nic. 

tf  i . T H  E  minerals  which  contain  the  larg  eft  quantity 
of  arfenic  'are  cobalts  and  white  pyrites  ;  although  it  is 
alib  contained  in  other  crcs,  ir  being  one  of  the  mine- 
lalifing  fubfiances.  But  as  coba.it  muft  be  roailed  to 
obtain  the  fulphur  it  contains,  the  arfenic  alib  which 
riles  daring  this  toneiac'tion  is  collected,  as  we  lhall 
i^e  i;i  part  III.  (SMELTING  oi  O:IES),  ana  the  particu 
lar  articles  of  each  of  the  metallic  iubitances  nieniion- 
cJ  in  this  article. 

I.  Regulus  cf  arfenic  is  found  native.  It  is  of  a 
leaden  colour  ;  it  barns  with  a  final  1  Mame  ;  and  is-  dif- 
iipa-eJ,  leaving  generally  a  very  frnall  quantity  of  calx 
t-.f  bifm'ith,or  of  c;!k  of  cobalt,  and  a  very  little  iilver. 
Vvhea  it  is  of  a  ibli-.l  rtnd  teUaceous  texiurc,  it  has 
been  improperly  called  tjli-.wtT  colalt,  in  German 
fcherbewfbalt*  II.  Calx  o,1  ar ionic  isiound  in  iorm  < -f 
powder*;  native  rlc  vv.r:,  of  arfenic,  or  cf  indurated  fe- 
n»itr;m  parent  crylfa  S  ;  native  cryllalline  arfenic. 
Ill .  Galx  of  arjfe  :  -axed,  i.  With  f  ilphur  ;  when 
\cllov.',  U  is  culled  Qri-ini*ntj>  \vheii  red,  it  is  called 
O  o 


C     444     ] 

tialiw  realgar  :  the  difference  of  colour  dedends  o»> 
the  proportion  of  the  two  component  parts.  2.  With 
calx  of  tin  ;  tin-grains.  3.  With  fulphur  and  iilver, 
in  the  red  filver  ere.  4.  With  calx  of  lead,  in  the  lead- 
fpar.  5.  With  calx  of  cobalt,  in '  the  efflorefcence  of 
cobalt.  IV.  Arfenic  is  miner alife'd,  j .  With  fiilphii- 
xated  iron ;  arfenical  pyrites.  2.  With  iron  only; 
white  pyrites,  or  mifpickle.  3.  With-  cobalt,  in  al- 
Hicil  all  cobalt-ores.  4.  With  filver.  5.  With  cop 
per.  6.  With  antimony. 

§  2.  Arfenic  may  be  feparated  from  its  ore  or  earthy 
matter  with  which  it  happens  to  be  mixed,  by  fub- 
limation,  according  to  the  following  proceis  by  Mr 
Cramer. 

"  Do  every  thing  as  was  fatd  about  mercury,  or 
fulphur  ;  but  let  the  veifel  which  is  put  into  the  fire 
with  the  ore  in  it  be  of  earth  or  ftone,  and  the  reci 
pient  be  of  glafs,  and  of  a  middling  capacity.  Nor  is 
it  necefTary  that  this  fhould  be  filled  with  water,  fo  it 
be  but  well  luted.  The  fire  mud  likewife  be  ftronger 
and  continued  longer  than  for  the  extracting  or'  ful 
phur.  Nevertheless,  every  kind  of  arfer.ic  cannot  be 
extracted  in  a  conlinedfire  :  for  it  adheres  to  the  ma 
trix  more  ftrongly  th.ui  fulphur  and  mercury.  You 
will  find  in  the  part  of  the  veflel  which  is  more  re 
mote  from  the  fire  pulverulent  and  fubtile  flowers  of 
ar&.nic  ;  but  there  will  adhere  to  the  poilerior  of  the 
v  neck  of  the  retort  fmall  folid  malfes,  fnining  like  frnall 
cryftals,  traniparent,  fometimes  gathered,  into  a  falid 
,  iliblimate,  and  perfediy  whit?,  if  the  ore  of  the  arfe- 
t  .nic  was  perfectly  pure  ;  which  neverthelefs  happens 
very  feldoin.  The  Mowers  are  moft  commonly  thin, 
and  of  a  grey  colour  :  which  proceeds  from  the  phlo- 
-gi  (lion  mixed  .with  the  mafs.  They  are  often  of  a  ci- 
tran  or  of  ii  golden  colour,  which  is  a  fign  that  there 
is  in  the  mixture  fome  mineral  fulphur:  and  if  the 
fablmate  be  red  or  yellovV,  it  is  a  fign  of  much  ful 
phur. 

«  As 


t     445     J 

"  As  all  the  arfenic  contained  in  the  ore  is  not  ex 
pelled  in  cloie  velTels,  you  muft  weigh  the  relidaum  ; 
then  roatl  it  in  a  crucible  till  it  fmokea  no  longer,  or 
rather  in  an  earthen  flat  veflel  not  glazed,  and  in  a 
ftrong  fire  to  be  ftirred  now  and  then  with  a  poker, 
and  then  weigh  it  when  grown  cold  :  you  will  be  able 
thus  to  know  how  much  arfenic  remained  in  the  dole 
veffel,  unkft  the  ore  contain  bifmuth." 

If  the  arfenic  be  .fulphurated,  it  may  be  purified  bf 
triturating  it  with  mercury  or  with  fixed  alkali,  and 
by  fubliming  the  arfenic  from  the  remaining  fulphu- 
rated  mercury  or  alkali.  The  method  of  abtaining  a 
regulus  of  arfenic  is  defcribed  at  the  article  RSGVLUS  tf 
jlrfnlc. 


P    A     R     T.       III. 
SMELTING  OF  ORES. 


HAviNG  fliown  the  nature  of  the  principal  metalli^, 
minerals,  and  the  fubftances  of  which  they  are 
compofed  ;  and  alfo  explained  the  procefles  by  which 
an  exacl:  analyfis  of  thefe  compound  minerals  may  be 
made,  and  the  nature  and  quantity  of  the  contained 
metals  may  be  known  ;  in  order  to  complete  what  re- 
•lates  to  this  important  fubj eft,  we  fhall  defcribe  in  this 
Part  the  principal  operations  by  which  metals,  &c. 
are  obtained  "  in  the  great/'  as  it  is  called,  or  for 
commercial  purpofes.  What  we  (hall  fay  upon  this 
fubjeft  will  chiefly  be  extracted  from  a  7ra?///£  on  tie 
Smelting  of  Ores,  by  Scbluttcr>  tran-flated  from  the 
O  o  2  German 


C     44<5     3 

German  into  French  by  M.  Hellot ;  becaufe  this,  of 
"all  the  modern  works  upon  that  fubjec~r,  appears  to  be 
the  moft  exact.  We  faall  flrft  ckfcribe  the  opera 
tions  upon  pyritous  matters  for  the  extraction  of  fu.l- 
pliur,  &c.  and  afterwards  the  operations  by  which  me 
tallic  fubilances  are  extracted  from  ores  properly  fo  cal 
led. 


SECT.    I.      Extrafihn    of  fulplur  from    Pyrites   and 
other  Minerals* 

IN  order  to  obtain  fulphur  from  pyrites,  this  mine 
ral  ought  to  be  expofed  to  a  heat  fuHicient  to  fublime 
the  fulphur  or  to  make  it  diitil  in  vcffels,  which  mult 
be  clofe,  to  prevent  its  burning. 

Sulphur  Is  extracted  from  pyrites  at  a  work  at 
Schwart/ember,  in  Saxony,  in  the  high  country  ot* 
the  mines  ;  and  in  Bohemia  at  a  place  called  Alien- 
SditeL 

The  furnaces  employed  for  this  operation  are  ob- 
Jong,  like  vaulted  galleries ;  and  in  the  vaulted  roofs 
are  made  feveral  openings.  Thefe  are  czMedfurjuues 
for  extraftingfiilphur. 

In  thefe  furnaces  are  placed  earthen-ware  tubes,  fill 
ed  with  pyrites  broken  into  pieces  of  the  fr/e  of  iinall 
nuts.  Each  of  thefe  tubes  contains  about  50  pounds 
of  pyrites.  They  are  placed  in  the  furnace  iilmofl  ho- 
ri/cntally,  and  have  icareely  more  than  an  inch  of  tie- 
icent.  The  ends,  which  come  out  of  the  furnace  five 
or  fix,  inches,  become  gradually  narrower.  Withm 
each  tube  is  fixed  a  piece  of  baked  earth,  in  form  of  it 
itar,  at  the  place  where  it  begins  to  become  r.arrow- 
tr,  in  order  to  prevent  the  pyrites  from  failing  our, 
or  choakir.'g  the  mouth  of  the  tube.  To  each  tube  is 
fitted  a  receiver  covered  with  a  leaden  pipe,  pierced 
with  a  frnall  hole  to  give  air  to  the  fulphur.  The 
other  end  of  the  tube  is  exactly  clofed.  A  moderate 
jGre  is  made  with  wood,  and  in  eight  hours  the  fuj. 

phui 


C     447     ] 

pbur  of  the  pyrites  is  found  to  have  paifed  into  the  rs- 
ceivers. 

The  refiduum  of  the  pyrites,  after  the  diftilLition, 
is  drawn  out  at  the  large  end,  and  fre(h  pyrites  is 
put  in  its  place.  From  this  refiduum,  which  is  called 
btfrititigs  of  fulphur^  vitriol  is  extracted. 

The  1 1  tubes  into  which  were  put,  at  three  feveral 
di foliations,  in  all  nine  quintals,  or  900  pounds  of 
pyrites,  yield  from  100  to  150  pounds  of  crude  ful- 
phur,  which  is  fo  impure  as  to  require  to  be  purified 
by  a  fecond  di  ft  illation. 

This  purification  of  crude  fulpbuf  is  alfo  done  in  a 
furnace  in  form  of  a  gallery,  in  which  five  iron  cucur 
bits  are  arranged  on  each  fide.  Thefe  cucurbits  are 
placed  in  a  doping  direction,  and  contain  about  eight 
quintals  and  a  half  of  crude  fulphur.  To  them  are 
kited  earthen  tubes,  fo  dilbofed  as  to  anfwer  the  pur- 
pofe  of  capitals.  The  nofe  of  each  of  thefe  tubes 
is  inferted  into  an  earthen  pot  called  -&\t  fore-runner. 

This  pot  has  three  openings ;  namely  that  which 
receives  the  nofe  of  the  tube  ;  a  fecond  fmaller 
hole,  which  is  left  open  to  give  air  ;  and  a  third 
in  its  lower  part,  which  is  flopped  with  a  wooden 
peg. 

When  the  preparations  are  made,  a  fire  is  lighted 
about  feven  o'clock  in  the  evening,  and  is  a  liitle 
abated  as  foon  as  the  fulphur  begins  to  diftil.  At 
three  o'clock  in  the  morning,  the  wooden  pegs  which 
flop  the  lower  holes  of  the  fore-runners  are  for  the 
firll  time  drawn  out,  and  the  fulphur  flows  out  of  each 
of  them  into  an  earthen  pot  with  two  handles,  placed 
below  for  its  reception.  In  this  diitillation  the  fire 
jriuft  be  moderately  and  prudently  conducted  ;  other-. 
wifelefs  fulphur  would  be  obtained,  and  it  alfo  would 
.be  of  a  grey  colour  and  not  of  the  fine  yellow  which. 
it  ought  to  have  when  pure.  The  ordinary  lofs  in 
the  purification  of  eight  quintals  of  crude  fulphur  is 
at  moft,  one  quintal. 

003  When 


t    44*    3 

When  all  the  fulphur  has  flowed  out,  -and  has  coolccf 
£  little  in  the  earthen-pots,  it  is  caft  into  moulds  made 
of  beech  tree,  which  have  been  .previoufly  dipt  in  wa- 
ter  and  fet  to  drain.  As  foonas  the  fulphur  is  cooled 
in  the  moulds,  they  are  opened,  and  the  cylinders  of 
fulphur  are  taken  out  and  put  up  in  cafks.  Thefe  are 
called  roll-lrhaftons. 

As  fulphur  is  not  only  in  pyrites,  but  alfo  in  molt 
metallic  minerals,  it  is  evident  that  it  might  be  ob 
tained  by  works  in  the  great  from  the  different  ores 
\vhichcontainimich  of  it,  and  from  which  it  muft  be 
feparated  previoufly  to  their  fufion  :  but  as  fulphur  is 
of  little  value,  the  trouble  of  collecting  it  from  ores 
is  feldom  taken.  Smelters  are  generally  iatisfied  with 
freeing  their  eres  from  it,  by  expoiing  them  to  a  fire 
fufficient  to  expel  it.  This  operation  is  called  torre*^ 
fafticin,  or  roajling  of  ores. 

There  are,  however,  ores  which  contain  fo  much 
fulphur,  that  part  of  it  is  actually  collected  in  the  or 
dinary  operation  of  roafting,  without  much  trouble 
for  that  purpofe.  Such  is  the  ore  of  Ramelfberg  in 
the  country  of  Hartz. 

This  ore,  which  is  of  lead,  containing  filver,  is 
partly  very  pure,  and  partly  mixed  with  cupreous  py 
rites  and  filver  ;  hence  it  is  neceffary  to  roalt  it. 

Tluroafthig  is  performed  by  laying  alternate  ftrata 
of  ore  and  wood  upon  each  other  in  an  open  field, 
taking  care  to  diminiih  the  fize  of  the  ftrata  as  they 
rife  higher ;  fo  that  the  whole  mafs  (hall  be  a  qua 
drangular  pyramid  truncated  above,  whofe  bafe  is 
about  31  feet  fquare.  Below,  fome,  paffages  are  left 
open,  to  give  f;ee  entrance  to  the  air;  and  the  fides 
•and  top  of  the  pyramid  are  covered  over  with  fmall 
ore,  to  concentrate  the  heat  and  make  it  laft  longer. 
In  the  centre  of  this  pyramid  there  is  a  channel  which 
defcends  vertically  from  the  to  top  the  bafe.  When 
all  is  properly  •.  rianged,  ladlefuls  of  red-hot  fcoria 
frcin  the  imelting  furnace  are  throve  dov.-n-the  chan 
nel* 


C    449    3. 

nel,  by  which  means  the  ihrubs  and  wood  placed  below 
for  that  purpoie  are  kindled,  and  the  fire  is  from  them, 
communicated  to  all  the  wood  of  the  pile,  which  con 
tinues  burning  till  the  third  day.  At  that  time  the 
fulphur  of  the  mineral  becomes  capable  of  burning 
fpontaneoufly,  and  of  continuing  the  fire  after  the 
wood  is  confumed. 

When  this  roatting  has  been  continued  15  days 
•the  mineral  becomes  greaiy;  that  is,  it  is  covered 
over  with  a  kind  of  varnifh  ;  20  or  25  holes  or  hol 
lows  are  then  made  in  the  upper-part  of  the  pile  in 
which  the  fulphur  is  collected.  From  thefe  cavities 
the  fulphur  is  taken  out  thrice  every  day,  and  thrown 
into  water.  This  fulphur  is  not  pure,  but  crude  j  and 
is  therefore  fent  to  the  manufacturers  of  fulphur,  to  be 
purified  in  the  manner  above  related. 

As  this  ore  of  Rameliberg  is  very  fulphureons,  the 
firft  roafting,  v.  hich  we  are  now  defcribing,  lafts  three 
months;  and  during  this  time,  if  much  rain  has  not 
fallen,  or  if  the  operation  has  not  failed  by  the  pile 
failing  down  or  cracking,  by  which  the  air  has  fo 
much  free  accefs,  that  the  fulphur  is  burnt  and  con- 
fumed,  from  10  or  20  quintals  of  crude  fulphur  are  by 
this  method  collected. 

The  fulphur  of  this  ore,  like  that  of 'mod  others, 
was  formerly  neglected,  till  in  the  year  1570,  a  per- 
ion  employed  in  the  mines  called  Chrijiop.cr  Sander 
difcovered  the  method  of  collecting  it,  nearly  as  it  is- 
done  at  preient. 

Metallic  minerals  are  not  the  only  fubftances  from 
which  fulphur  is  extracted.  This  matter  is  diffufed 
in  the  earth  in  fuch  quantities,  that  the  metals  cannot 
abforb  it  all.  Some  fulphur  is  found  quite  pure,  and 
in  different  forms,  principally  in  the  neighbourhood 
of  volcanoes,  in  caverns,  and  in  mineral  waters.  Such 
are  the  opaque  kind  called  •vlrgin-fufykur  ;  the  tranfpa- 
rcnt  kind  called  fulphur  cf  ^uiio  ;  and  the  native 
flowers  of  fulphur,  as  thoie  of  the  waters  of  Aix-la- 

Chapelle. 


[     450     ] 

Chapelle.  It  is  alib  found  mixed  with  different 
earths.  Here  we  may  obferve,  t'.at  all  thofe  kinds  of 
fulphur  which  are  not  minerali/ed  by  metallic  fub- 
ftances,  are  found  near  volcanoes,  or  hot  mineral  wa 
ters,  and  confequently  in  places  where  nature  ieerns 
to  have  formed  great  fubterranean  laboratories ;  in 
which  fulphureous  minerals  may  be  analysed  and  de- 
compofed,  and  the  fulphur  feparated,  in  the  manner 
in  which  it  is  done  in  final!  in  our  works  and  labora 
tories.  However  that  be,  certainly  one  of  the  bed 
and  moft  famous  fulphur-mines  in  the  world  is  that 
called  Sofatara.  7"he  Abbe  Nollet  has  published, 
in  the  Memoirs  of  the  Academy,  fonie  intereiling  ob- 
fcrvations  upon  this  fubjccl,  which  we  iliall  here- 
abridge. 

Near  Puzzoli,  in  Italy,  is  that  great  and  famous 
mine  of  fulphur  and  alum  called  at  prefent  Solfatara. 
It  is  a  fmall  oval  plain,  the  greater!  diameter  of  which 
is  about  400  yards,  railed  about  300  yards  above  the 
level  of  the  fea.  It  is  Surrounded  by  high  hills  and 
great  rocks,  which  fall  to  pieces,  and  whole  fragments 
form  very  fteep  banks.  Almoft  all  the  ground  is  bare 
and  white,  like  marie,  and  is  every  where  fenfibly 
warmer  than  the  atm*>fphere  in  the  greateft  heat  of 
furnmer,  fo  that  the  feet  of  perfons  walking  there  are 
burnt  through  their  fhoes.  It  is  impoilible  not  to 
obfcrve  the  fulphur  there;  for  every- where  may  be  per 
ceived  by  the  fmell  a  fulphureous  vapour,  which  rifes 
to  a  considerable  height,  and  gives  reafon  to  believe 
that  there  is  a  fubterraneous  nre  below,  from  which 
that  vapour  proceeds. 

Near  the  middle  of  this  field  there  is  a  kind  of  ba- 
fon  three  or  four  feet  lower  than  the  reft  of  the  plain, 
in  which;  a  found  may  be  perceived  when  a  perfon 
walks  on  it,  as  if  there  were  under  his  feet  feme  great 
cavity,  the  root  of  which  was  very  thin.  After  that 
.the  lake  Agnano  is  perceived,  whofe  waters  feem  to 
toil.  Thefe  waters  are  indeed  hot,  but  not  fo  hot  as 

boiling 


[     4S»     3 

boiling  water.  This  kind  of  ebullition  proceeds  from 
vapours  which  rife  from  the  bottom  of  the  lake, 
,  which  being  let  in  motion  by  the  action  of  fubterra- 
nean  fires,  have  force  enough  to  raife  all  that  mafs  of* 
water.  Near  this  lake  there  are  pits,  not  very  deep, 
from  which  fulphnreous  vapours  are  exhaled.  Per- 
ibns  who  have  the  itch  come  to  thefe  pits,  and  receive 
the  vapours  in  order  to  be  cured.  Finally,  there  are 
.Ibme  deeper  excavations,  whence  a  ibft  ftone  is  pro 
cured  which  yields  fulphur.  From  thefe  cavities  va 
pours  exhale,  and  iiTue  out  with  noife,  and  which  are 
nothing  elfe  than  fulphur  fubliming  through  the  cre 
vices.  This  fulphur  adheres  to  the  fides  of  the  rock?, 
where  it  forms  enormous  malTes:  in  calm  weather,  the 
vapours  may  be  evidently  feen  to  rife  25  or  30  feet 
from  the  iurface  of  the  earth. 

Thefe  vapours,  attaching  themfelves  to  the  fides  of 
rocks,  form  enormous  groups  of  fulphur,  which  fome 
•  times  falls  dov/n  by  their  own  weight,  and  render  thefe 
places  of  dangerous  accefs. 

In  entering  the  Solfatara,  there  are  warehonfes  and 
buildings  creeled  fcr  the  refining  of  fulphur. 

Under  a  great  med,  or  hangar,  fupported  by  a  wall 
behind,  and  open  on  the  other  three  fides,  the  fulphur 
is  procured  by  diftillation  from  the  foil  ft  ones  we  men 
tioned  above.  Thefe  ftones  are  dug  from  under  ground ; 
and  thofe  which  lie  en  the  iurface  of  the  earth  are 
negkcled.  Thefe  laft  are,  however,  covered  with  a  ful 
phur  ready  formed,  and  of  a  yellow  colour  :  but  the 
workmen  fay  they  have  loft  their  ftrength,  and  that  the 
fulphur  obtained  from  them  is  not  of  fo  good  a  quality 
as  the  fulphur  obtained  from  the  ftones  \vhicharedug 
out  of  the  ground. 

Thefe  lail  mentioned  are  broken  into  lumps,  and 
put  into  pots  of  earthen  ware,  containing  each  about 
20  pints  Paris  meafure.  The  mouths  of  thele  pots  are 
;is  \vide  as  their  bottoms;  but  their  bellies,  or  middle 
parts,  are  wider.  They  are  covered  with  a  lid  of  the 

iame 


C    45^    1 

fame  earth,  well  luted,  and  are  arranged  in  two  paral 
lel  lines  along  two  brick  walls,  which  form  the  two 
fides  of  a  furnace.  The  pots  are  placed  within  thefe 
walls ;  fo  that  the  centre  of  each  pot  is  in  the  centre 
of  the  thicknefs  of  the  wall,  and  that  one  end  of  the 
pots  overhangs  the  wall  within,  while  the  oiher  end 
overhangs  the  wall  without.  In  each  furnace  ten  ot 
thefe  pots  are  placed  ;  ^that  is,  five  in  each  of  the  two 
walls  which  form  the  two  fides  of  the  furnace.'*  Be 
twixt  thefe  walls  there  is  a  fpace  of  15  or  18  inches  ; 
which  fpace  is  covered  by  a  vault  refting  on  the  two 
walls.  The  whole  forms  a  furnace  feven  feet  long,  two 
feet  and  a  half  high,  open  at  one  end,  and  fhut  at  the 
other,  excepting  a  fmall  chirnney  through  which  the 
fmoke  pafios. 

Each  of  thefe  pots  has  a  mouth  in  its  upper  part 
without  the  furnace, in  order  to  admit  a  tube  of  1 8  lines 
in  diameter  and  a  foot  in  length,  which  communicates 
with  another  pot  of  the  fame  fize  placed  without  the 
building,  and  pierced  with  a  round  hole  in  its  bafe  of 
.15  or  18  lines  diameter.  Laftly,  to  each  of  thefe  laft- 
mentioned  pots  there  is  a  wooden  tub  placed  below}  in 
a.  bench  made  for  that  purpofe. 

Four  or  five  of  thefe  furnaces  are  built  under  one 
hangar,  or  ftied.  Fires  are  kindled  in  each  of  them  at 
the  fame  time  ;  and  they  are  thrown  down  after  each 
diftillation,  either  that  the  pots  may  be  renewed,  or 
that  the  refiduums  may  be  more  eafily  taken  out. 

The  fire  being  kindled  in  the  furnace,  heats  the  firfl 
pots  containing  the  fiilphureous  ftones  The  fulphur 
rifes  in  fumes  into  the  upper  part  of  the  pot,  wrhence 
it  paffes  through  the  pipe  of  communication  into  the 
external  veifel.  There  the  vapours  are  condenfed,  be 
come  liquid  and  flow  through  the  hole  below  into  the 
tub,  from  which  the  fulphur  is  eafily  turned  out,  be- 
caufe  the  form  of  the  vefiel  is  that  of  a  truncated  cone 
whofe  narrower  end  is  placed  below,  and  becaufe  the 
hoops  of  the  tub  are  fo  fattened  that  they  may  be  oc- 

cafionally 


C     453     ] 

cafionally  loofened.  The  mafs  of  iulphur  is  then  car 
ried  to  the  buildings  mentioned  before,  where  it  is  re- 
melted  for  its  purification,  and  caft  into  rolls,  fuch  as 
we  receive  it. 

Extraflicn  of  FITZIOL  from  pyritss.  See  CHEMI 
STRY, 

Extraction  of  ALUM  from,  pyritoiu  fubjlances  and 
from  aluminous  tarths.  See  CHEMISTRY. 

SECT.  II.      Smelting  'if  Ores  in  gsncraL 

§  i.  As  ores  confift  of  metallic  matters  combined 
with  fulphur  and  arfeilic,  and  are  betides  intermixed 
with  earthy  and  (tony  fub-tances  of  ail  kinds,  the  in 
tention  of  all  the  operations  up-vii  tlicie  compound  bo 
dies  is  to  leparate  the.'e  different  fubHancfS  fi  m  eacli 
otiier.  This  is  --:fl\^c-;d  07  feveral  operations  founded 
on  the  known  pr  perties  of  iho/e  .ublVm-jes.  We  now 
proceed  to  give  a  general  idea  of  tlicfe  feveral  opera 
tions. 

Firft  of  all,  the  ore  is  to  be  f.parat'  d  from  the 
earths  and  (tones  accidentally  adherent  to  it;  and  when 
thde  foreign  fub.uinces  are  in  large  m.ifies,  and  are  not 
very  intimately  mixed  in  {mail  particles  with  the  ore, 
this  reparation  may  be  accompli,  hed  by  mechanic.:! 
m  'uns.  Tills  ought  always  to  be  the  firil  operation, 
imlefs  the  adhereat  iubitance  be  capable  of  isrving  as 
a  flux  to  the  ore.  If  the  unmetallic  eardis  be  inti 
mately  mixed  with  the  ore,  this  mad  nj_eifirily  be 
broken  and  divided  into  fmall  particles.  This  opera- 
tivj.i  is  performed  by  a  machine  v/liich  moves  pe files, 
caliei//-?^;"^/  or//-7.v^»..r/.  Af:er  this  operation,  wheii 
ta?  patts  of  the  miaeral  are  fpecilically  heavier  than 
tho;c  of  the  unmetallic  earch  or  Hone,  thcfj  latter  may 
.b^feparated  from  the  ore  by  wafhing  in  canals  through 
which  wa'cr  flows.  With  regard  to  this  wafh'iig  of 
ores,  it  is  neeeilary  to  obfjrve,  .that  it-canmt.  facceed 
but  when  the  ore  is  fonfibly  heavier  than  the  foreign 

matters. 


[     454     ] 

matters-  But  tie  contrary  happens  frequently,  as  well 
becaufe  quarts  and  fpar  are  naturally  very  ponderous, 
as  becaufe  the  metallic  matter  is  proportionally  fo 
much  lighter  as  it  is  combined  with  more  fulphur. 

When  an  ore  happens  to  be  of  this  kind,  it  is  necef- 
fary  to  begin  by  roalting  it,  in  order  to  deprive  it  of 
the  greateft  part  of  its  fuiphur. 

It  happens  frequently  that  the  pyritous  matters  ac 
companying  the  ore  are  fo  hard  that  they  can  fcarcely 
be  pounded.  In  this  cafe  it  is  neceiTary  to  road:  it  en 
tirely,  or  partly,  and  to  throw  it  red  hot  into  cold  wa 
ter  ;  by  which  the  ftones  are  fpltt,  and  rendered  much 
jr.ore  capable  of  being  pulveriied. 

Thus  it  h-.ippens  very  frequently,  that  mailing  is  the 
firft  operation  to  which  an  ore  is  expole-J. 

When  'he  iubftanee  rf  the  ore  is  very  iuP.ble,  this 
firft  operation  may  be  dilpeiaed  \v  >h.  and  die  matter 
may  be  immediately  filled  without  any  previous  roaft- 
ing,  or  at  lea  ft  with  a  very  {light  MK-.  For,  to  effect 
ihis  fufion,  it  is  iKee.Ta.ry  thai  it  retain  a  great  quan 
tity  of  its  fulphur,  which,  with  the  other  fluxes  added, 
ferves  to  deilroy  or  convert  into  fcoria  a  confidcrable 
part  (-{'the  fkmy  matter  of  :hc  mineral,  ai.d  to  rerhice 
the  rcil  into  a  brittle  fubflance,  which  i?  ca;led  the  matt 
cf  lead  or  of  copper,  or  rthei  metal  (ROtitsine'd  in  tl.-e 
ore.  This  matt  is  theicf^rr:  an  ir.tr  rn',diar  -  matter  be 
twixt  the  mineral  tnd  the  meta'i  ;  icr  u  c  in^-::-l  is  there 
concentrated,  and  irixcd  with  lei's  ftfekft  ^natter  than 
it  was  in  the  ere.  But  as  this  matt  is  always  Inlpliu- 
reous,  the  metai  whidi  ir  contains  cannot  have  its  me 
tallic  f  roperties.  Therefore  it  rrnit  be  roarled  ieveral 
times  to  tv.--.perate  viie  fulphur,  before  it  is  remelted, 
\vhentliepurcineta1.  is  required.  This  funon  cf  an  ore 
not  r<  alted,  or  but  ilightiy  icaiied,  is  called  crude  fu- 
Jkn. 

We  may  here  obferve  upon  the  fub'ecl  cf  wailiing 
arid  reading-  oi  OILS,  f li.it  as  nrfciiic  is  heavier  than  lui- 
phur,  and  has  nearly  the  weight  t-f  niclais,  the  f  res  in 

v.i.ich 


C     455     J 

which  it  prevails  arc  generally  very  hcav",  and  ctnle- 
quently  are  fuiccpiihlc  of  being  wafhed,  'which  is  a 
great  advantage.  But  on  the  other  ride,  as  artenic  is 
capable  of  volaliring,  fcoriiying,  and  deitroying  many 
metals,  thefe  ores  have  diladvantages  in  the  roaiting 
and  fufion,  in  both  which  confiderable  lofs  is  caufed' 
by  the  arienic.  Some  ores  contain,  belides  arienic, 
other  volatile  femimetuls,  fuch  as  antimony  and  /inc.' 
Thefe  are  almoit  nntraclable,  and  are  therefore  neglec 
ted.  They  are  called  miners  rap&ces^  *'  rapacious 
ores." 

When  the  metal  has  been  freed  as  much  as  is  pof- 
iible  from  foreign  matters  by  theie  preliminary  opera 
tions,  it  is  to  be  completely  purified  by  fulions  more 
or  lefs  frequently  repeated  ;  in  which  proper  additions 
are  made,  either  to  abforb  the  re  11  of  the  fulphur  and 
arfenic,  or  to  complete  the  vitrification  or  fcorification 
of  the  immetallic  {tones  and  eaith. 

Laftly,  as  ores  frequently  contain  feveral  different 
metals,  thefe  are  to  be  feparated  from  each  other  by 
proceffes  fuited  to  the  properties  of  thefe  metals,  of 
which  we  {hall  fpeak  more  particularly  as  we  proceed 
in  our  examination  of  the  ores  of  each  metal. 

§  2.  To  facilitate  the  extraclion  of  metallic  fnb- 
ftances  from  the  ores  and  minerals  containing  them, 
fome  operations  previous  to  the  fufon  or  fmelting  of 
thefe  ores  and  minerals  are  generally  neceiFary.  Thefe 
operations  confift  of,  i.  r£hz  feparation  of  the  ores  and 
metallic  matters  frc.m  the  adhering  unmetailic  earths 
and  ftones,  by  hammers  and  other  mechanical  inftru- 
ments,  and  by  \vaihing  with  water.  2.  Their  divi- 
Jwn  or  reduction  into  fmaller  paits  by  contufion  and 
trituration,  that  by  another  walhing  with  water  they 
may  be  more  perfectly  cleanfed  from  extraneous  mat 
ters,  and  rendered  fitter  for  the  fubfequent  operations, 
calcination  or  reading,  and  fufion.  3.  Roafting  or  cal 
cination  ;  the  ufes  of  which  operation,  are,  to  expel,  the 
volatile  ufelcfs,  or  noxious  fubftances,  as  water,  vitrio- 
P  p  lie 


He  acid,  fulphur,  and  arfenic  ;  to  render  the  ore  mo~e 
friable,  and  fitter  for  the  fubfequent  contufion  and  iu- 
ficn;  and,  lailly,  to  calcine  and  deftroy  the  viler  me 
tals,  for  inftance  the  iron  of  copper-ores,  by  means 
of  the  fire,  and  of  the  fulphur  and  arfenic.  Stones,  as 
quartz,  and  flints,  containing  metallic  veins  or  particles 
are  frequently  made  red-hot,  and  then  extinguiilied  in 
cold  water,  that  they  may  be  rendered  fufficiently  fri 
able  and  pulverable,  to  allow  the  feparation  of  the  me 
tallic  particles. 

Roafting  is  unneceilary  for  native  metals  ;  for  fome 
of  the  richer  gold  and  filver  ores;  for  fome  lead-ores 
the  fulphur  of  which  may  be  feparated  during  the  fu- 
fion;  and  for  many  calciform  ores,  as  thefe  do  not  ge 
nerally  contain  any  fulphur  or  arfenic. 

In  the  reading  of  ores,  the  following  attentions  muft 
be  given,  i.  To  reduce  the  mineral  previoufly  into 
fmall  lumps,  that  the  furface  may  be  increafed  ;  but 
they  muft  not  be  fo  fmall,  nor  placed  fo  compactly,  as 
to  prevent  the  pafiage  of  the  air  and  flame.  2.  The 
larger  pieces  muft  be  placed  at  the  bottom  of  the  pile, 
where  the  greateft  heat  is.  3.  The  heat  muft  be  gra 
dually  applied,  that  the  fulphur  may  not  be  melted, 
which  would  greatly  retard  its  expulfion  ;  and  that  the 
fpars,  fluors,  and  ftcnes,  intermixed  with  the  ore,  may 
not  crack,  fly,  and  be  difperied.  4.  The  ores  not 
thoroughly  roailed  by  one  operation  muft  be  expofed 
to  a  fecond.  5.  The  fire  may  be  increafed  towards 
the  end,  that  the  noxious  matters  more  ftrongly  ad 
hering  may  be  expelled.  6.  Fuel  which  yields  much 
flame,  as  wood  and  foflil  coals  free  from  fulphur,  is 
faid  to  be  preferable  to  charcoal  or  coaks.  Sometimes 
cold  water  is  thrown  on  the  calcined  ore  at  the  end 
of  the  operation,  while  the  ore  is  yet  hot,  to  render 
it  more  friable. 

No  general  rule  can  be  given  concerning  the  dura 
tion  or  degree  of  the  fire,  thefe  being  very  various  ac 
cording  to  the  difference  of  the  ores.  A  roafting  du 
ring 


iiitg  :i  tVw  hours  or  days  is  firfacient  for  many  ores  ; 
while  lome,  fuch  as  the  ore  of  Ramelfberg,  require 
thai  it  fhoukl  b.  continued  during  feveral  months. 

tSchhit'er  enumerates  five  methods  of  roafting  ores. 
r.  By  C'mflrucYm^  a  pile  of  oi-ss  and  fiul  placed  in  al 
ternate  ilrnia,  ii\  thj  open  air,  without  any  furnace. 
2.  By  confining  I'uch  a  pile  within  walls,  hut  without: 
a  roof.  3.  By  jiliu'ln^  the  pile  under  a  roof,  without 
Literal  walls  4.  By  placing  the  pile  in  a  furnace  con 
fiding  of  wails  and  a  roof.  5.  By  roafting  the  ore  in 
a  reverfeeratory  furnace,  in  which  it  mud  be  continually 
ilirred  with  an  iron  rod. 

Several  kinds  of  fufions  of  ores  may  be  diftmguifn- 
ed.  i.  When  a  fulphureous  ore  is  mixed  with  much 
earthy  matter,  from  which  it  cannot  be  eafily  fepara 
ted  by  mechanical  operations,  it  is  frequently  melted, 
in  order  to  difengage  it  from  thefe  earthy  matters,  and 
to  concentrate  its  metallic  contents.  By  this  fufion, 
ibme  of  the  fulphur  is  diffipated,  and  the  ore  is  redu 
ced  to  a  ftate  intermediate  betwixt  that  of  ore  and  of 
metal.  It  is  then  called  a  malt  (lapis  fulphureo-metdlU' 
ens)  ;  and  is  to  be  afterwards  treated  like  a  pure  ore 
by  the  fecond  kind  of  fufion,  which  is  properly  the 
i'melttng,  or  extraction  of  the  metal  by  fufion.  2.  By 
this  fufion  or  fmelting,  the  metal  is  extracted  from  the 
ore  previoully  prepared  by  the  above  operations,  if 
thefe  be  neceifary.  The  ores  of  fome  very  fufible  me 
tals,  as  of  bifmuth,  may  be  fmelted  by  applying  a  heat 
iufficient  only  to  melt  the  metals,  which  are  thereby 
feparated  from  the  adhering  extraneous  matters.  This 
reparation  of  metals  by  fufion,  without  the  vitrification 
of  extraneous  matters,  may  be  called  eliquatlon.  Ge 
nerally,  a  complete  fufion  of  the  ore  and  vitrification 
of  the  earthy  matters  are  neceflary  for  the  perfect  fe- 
paration  of  the  contained  metals.  By  this  method, 
inetals  are  obtained  from  their  ores,  fometimes  pure, 
and  fometimes  mixed  with  other  metallic  fubdances, 
from  which  they  maft  be  afterwards  feparated  ;  as  we 
Pp  2  (halt 


[     458     ] 

fee  when  we  treat  of  the  extraction  of  particu- 
lir  metals.  To  procure  this  reparation  of  metals  from 
ores,  thefe  nmft  be  fo  thinly  liquefied,  that  the  fmall 
metallic  particles  may  difeng^ge  themlelves  fn»m  the 
fcoria;  but  it  muft  not  be  fo  thin  as  to  allow  the  me 
tal  to  precipitate  before  it  be  perfectly  difengaged 
irom  any  adhering  extraneous  matter,  or  to  pervade 
and  deitroy  the  containing  veflels  and  furnace.  Some 
v>res  are  fufficiently  fuiible  ;  but  others  require  certain 
additions  called  faxes,  to  promote  their  fufion  and  the 
v\\ .rilication  of  their  unmetallic  parts  ;  and  alib  to  ren 
der  the  fcoria  fufficiently  thin  to  allow  the  feparation 
of  the  metallic  particles. 

Different  fluxes  are  fuitable  to  different  ores,  accor- 
ding  to  the  quality  of  the  ore,  and  of  the  matrix,  or 
ilone  adherent  to  it. 

The  matrixes  of  two  different  ores  of  the  fame  me 
tal  frequently  ferve  as  fluxes  to  each  other;  as,  for  in- 
.itance,  an  argillaceous  matrix  \vith  one  that  is  calca- 
reous  :  thefe  two  earths  being  difpofed  to  vitrification 
•when  niked,  though  each  of  them  is  fmgly  unfuftble. 
For  this  reafon,  two  or  more  different  or^s  to  be  fmelt- 
cd  are  frequently  mixed  together. 

The  ores  alfo  of  different  metals  require  different 
fluxes.  Thus  calcareous  earth  is  found  to  be  the  belt 
jilted  to  iron-ores;  and  fpars  and  fcoria  to  fuiible  ores 
of  copp:r. 

The  fluxes  mod  frequently  employed  in  the  fmelt- 
ing  of  ores  are,  calcareous  earths,  iluors  or  vitreous 
fpars,  quartz,  and  fand,  fuiible  ftones,  as  ilates,  bafal- 
tes,  thefeveral  kinds  of  fcoria,  and  pyrites. 

Cajcareous  earth  is  tiled  to  facilitate  the  fufion  rf 
ores  of  iron,  and  of  fome  of  the  poorer  ores  of  copper, 
and,  in  general,  of  ores  mixed  with  argillaceous  earths, 
or  with  felt  fpar.  This  earth  has  been  fometiines  add 
ed  with  a  view  of  feparating  the  fulphur,  to  which  it 
very  readily  unites  :  but  by  this  union  the  fulphur  is 
detained,  and  a  hepar  is  formed,  which  readily  diffolves 

iron 


C  '  4J9     ] 

Iron  and  other  metals,  and  fo  firmly  adheres  to  them,, 
thatthey  cannot  be  feparated  without  more  difficulty 
than  they  could  from  the  original  ore.  This  addition 
is  therefore  not  to  be  made  till  the  fulphur  be  previ- 
oufly  well  expelled. 

Filters  QIC  fujibk  fpars  facilitate  the  fufion  of  moft 
metallic  minerals,  and  aiib  of  calcareous  and  argilla 
ceous  earths,  of  ileatites,  afbeftus,  and  fome  other  un. 
fufible  ftones,  but  not  of  fiiiceous  earths  without  a* 
mixture  of  calcareous  earth. 

Quartz  is  fometimes  added  in  the  fufion  of  ferrugi 
nous  copper  ores,  the  ufe  of  which  is  faid  chiefly  to  be, 
to  enable  the  ore  to  receive  a  greater  heat,  and  to  give 
a  more  perfect  vitrification  to  the  ferruginous  fcoria.. 

Thc-fvfiMe-Jhn&i  zsJJates,  bafaltes,  are  fo  tenacious 
and  thick  when  fufed,  that  they  cannot  be  confidered 
properly  as  fluxes,  but  as  matters  added  to  lefien  the 
too  great  liquidity  of  fome  very  fufible  minerals. 

The  fcoria  obtained  in  the  'fufion  of  an  ore  is  fre 
quently  ufeful  to  facilitate  the  fafion  of  an  ore  of  the 
lame  metal,  and  fometincs  even  ores  of  other  metals. 

Sitbbnraied pyrites  greatly  promote  the  fufibility  of 
the  fcoria  of  metals,  from  the  falphur  it  contains.  It 
is  chiefly  added  to  diincultly-fufible  copper-ores,  to 
form  the  fulphureous  compounds  called  matts,  that  the 
ores  thus  brought  into  firilon  may  be  feparated  from 
the  adhering  earthy  matters,  and  that  the  ferruginous 
mutter  contained  in  them  may  be  deitroyed,  during 
the  fubfequent  calcination  and  fufion,  by  means  of  the 
fulphur. 

A*  in  the  ores  called  calciform,  the  metallic  matter 
exifts  in  a  calcined  ftate  ;  and  as  calcination  reduces 
the  metals  of  mineralifed  ores  (excepting  the  perfect 
metals )  to  that  ftate  alfo  ;  therefore  all  calciform  and 
calcined  ores  require  the  addition  of  fome  inflammable 
fubftance  to  reduce  them  to  a  metallic  ftate.  In  great 
works,  the  charcoal  or  other  fuel  ufed  to  maintain  the 
fire  produces  alfo  this  effect. 

P  p  3  Mttal* 


C    460    ] 

Metals  are  fometimes  added  in  the  fufion  of  ores  of 
ether  more  valuable  metals,  to  abforb  from  thefe  ful- 
phur  cr  arfenic.  Thus  iron  is  added  to  fulphurated, 
cupreous,  and  filver  ores.  Metals  are  alfo  added  in  the 
tulion  of  ores  of  other  more  valuable  metals,  to  unite 
with  and  collect  the  fmall  particles  cf  thefe  difperfed 
through  much  earthy  matter,  and  thus  to  affift  their 
precipitation.  With  thefe  intentions  lead  is  frequently 
added  to  ores  and  minerals  containing  gold,  filver,  or 
copper. 

Ores  of  metals  are  alfo  fometimes  added  to  alTift  the 
precipitation  of  more  valuable  metals.  Thus  antimony 
is  frequently  added  to  affift  the  precipitation  of  gold 
intermixed  with  other  metallic  matters.  Thus  far  of 
fmelting  of  ures  in  general. 

SECT.  III.     Smelting  of  Ores  of  Silver. 

§  I.  As  fiver,  even'  its  proper  ores,  as  always  al 
layed  with  fame  ether  metals  from  which  it  is  intend 
ed  to  be  fe  para  ted  alter  the  filver-ors  has  been -well 
•roaited,  it  muit  be  mixed  with  a  greater  or  lefs  quan 
tity  of  le  id  previous  to  its  fufion. 

Lead  has  the  fame  effect  in  fufion  of  gold  and  filver 
as  mercury  has  upon  thefe  metals  by  its  natural  fluidi 
ty  ;  that  is  to  fay,  it  unites  with  them,  and  feparates 
them  from  immetallic  matters,  which,  being  lighter, 
rife  always  to  the  furface.  But  lead  has  the  further 
advantage  of  procuring,  by  its  own  vitriiication,  that 
of  all  metallic  fubftances,  excepting  gold  and  filver. 
Hence  it  fellows,  that  when  gold  and  filver  are  ob 
tained  by  means  of  mercury,  they  ftill  remain  allayed 
with  other  metallic  fubftances ;  whereas  when  they  are 
obtained  by  fufion  and  fcormcation  with  lead,  they  are 
then  pure,  and  not  allayed  with  any  metals  but  with, 
each  other. 

In  proportion  as  the  lead,  which  has  been  united  to 
$he  geld  and  filver  of  the  oiv,  is  fcoriiicd  by  the. 


C    46'    ]  • 

aftion  of  the  lire,  and  promotes  the  fcorincation  of 
the  other  metallic  matters,  it  feparates  the  perfect 
metals,  and  'carries  with  it  all  the  others  to  the  fur- 
face.  There  it  meets  the  unmetallic  fubftances,  which 
it  likewife  vitrifies,  and  which  it  changes  into  a  per 
fect  fcoria,  fluid,  and  fuch  as  a  icoria  ought  to  be  to 
admit  all  the  perfect  metal  contained  in  it  to  precipi 
tate. 

When  all  heterogeneous  matters  have  been  thus 
difengnged  by  fcorification  with  lead,  the  perfect 
metals,  to  which  fome  lead  ftill  remains  united,  are 
to  he  funher  purified  by  the  ordinary  operation  of 
the  cupel. 

The  common  rule  for  the  fufion  and  fcorification  of 
filver-ore  with  lead,  is  to  add  to  the  ore  a  quantity  of 
lea  J.  fo  much  greater  as  there  is  more  matter  to  be  fco- 
ritied,  and  as  thefe  matters  are  more  refractory  and  of 
more  difficult  fufion.  Silver  ores,  or  thofe  treated  as 
fuch,  are  often  rendered  refractory  by  ferruginous 
earths,  pyritoiis  matters,  or  cobalts,  containing  al 
ways  a  confiderable  quantity  of  an  earth  which  is  un 
metallic,  very  fubde,  and  very  refractory,  and  which 
renders  a  confiderable  augmentation  cf  the  quantity  of 
lead  necelfary. 

The  quantity  of  lead  which  is  commonly  added  to 
fufible  iilver  ore?,  that  do  not  contain  lead,  is  eight 
times  the  quantity  of  the  ore.  But  when  the  ore  is 
refractory,  it  is  neceffary  to  add  twelve  times  the 
quantity  of  lead,  and  even  more  ;  alfo  glafs  of  lead, 
and  fluxes,  fuch  as  the  wrhite  and  black  fluxes  ;  ta 
which  however  borax  and  powder  of  charcoal  are  pre 
ferable,  on  account  of  the  liver  of  fulphur  formed  by 
thefe  alkaline  fluxes. 

It  is  necellary  to  obferve,  that  faline  fluxes  are  only 
ufed  in  fmall  operations,  on  account  of  their  dearnefs. 
To  thefe  are  fubftituted,  in  the  great  operations,  of 
which  we  now  treat,  fandiver,  fafible  fcoria,  and  other 
matters  of  little  value. 

Tlie 


The  greateft  part  of  filver  now  employed  in  com 
merce  is  not  obtained  from  the  proper  ores  of  lilver, 
which  are  very  fcarce;  but  from  lead  and  even  copper 
ores,  which  are  moreorlefs  rich  in  filver.  To  give  an 
idea  of  the  manner  of  treating  thefe  kinds  of  ores,  from 
which  filver  is  extracted  in  the  great  works,  we  (hall 
briefly  defcribe  here,  after  Schlutter,  the  fm  si  ting  of 
the  ore  of  Rarnelfberg,  which  contains,  as  we  have 
already  faid,  feveral  different  kinds  of  mctkls,  but 
particularly  lead  and  filver. 

When  this  mineral  has  been  difengaged  from  its 
fnlphur  as  much  as  poffible  by  three  very  long  read 
ings,  it  is  melted,  in  the  Lower  Hartz  in  Saxony,  in 
a  particular  kind  of  furnace,  called  a  furnace  for 
fmelting  upon  a  holhiu  or  caj/e.  The  mafonry  of  this 
furnace  is  compofed  of  large  thick  Hates,  capable  of 
fuftaming  great  heat,  and  cemented  together  by  clay. 
The  interior  part  of  the  furnace  is  three  feet  and  a 
half  long,  and  two  feet  broad  at  the  back  part,  and 
one  foot  only  in  the  front.  Its  height  is  nine  feet 
eight  inches.  It  has  a  foundation  of  mafonry  in  the 
ground  ;  and  in  this  foundation  channels  are  made 
for  the  evaporation  of  the  moifture.  Thefe  channels 
are  covered  over  with  ftones  called  covering  fonts. 
The  hollow  or  caffe,  which  is  made  above  thefe,  is 
formed  of  bricks,  upon  which  are  placed,  firlr,  a  bed 
of  clay  ;  then  a  bed  of  fmall  ore  and  fined  vitriols  ; 
and,  laftly,  a  bed  of  charcoal  powder  be.tt  down, 
called  light  Irafque.  The  anterior  wall  of  the  furnace 
is  thinner  than  the  others,  and  is  called  the  cLemife. 
The  back  wall,  which  is  pierced  to  give  pailage  to  the 
pipes  cf  two  large  wooden  bellows,  is  called  the  middle 
•wall.  When  the  furnace  is  thus  prepared,  charcoal 
is  thrown  into  the  hollow,  or  caiTe ;  which  being 
kindled,  the  fire  is  to  be  continued  during  three  hours, 
before  the  matters  to  be  fufed  are  added.  Then 
thefe  matters  are  thrown  in,  which  are  not  the  pure 
ore,  but  a  mixture  of  feveral  fubftanccs,  all  of  which, 

are 


C    463    J 

are  fomewhat  profitable.  The  quantity  of  theie  mat 
ters  is  furncient  ior  one  day's  work  ;  that  is,  for  a 
fufion  of  eighteen  hours;  and  it  confi'.ts  of,  i.  Twelve 
fchorbens  or  meafures  of  well  roafted  Ramelfoerg 
ore  (the  fchorben  is  a  meaiure  whole  contents  are 
two  feet  five  inches  long,  one  foot  feven  inches  broad, 
and  a  little,  more  than  a  foot  deep  :  it  is  equal  to  32 
quintals  of  that  country.  C(  logn  weight,  at  123 
p  unds  er.ch  quintal).  2.  Six  measures  of  icoria  pro 
duced  by  the  fmelting  of  the  ore  of  Upper  Hartz, 
which  is  rcfra&ory,  and  what  workmen  call  cold. 
3.  Two  meafures  of  knobben,  -which  is  an  impure 
fcoria  containing  fome  lead  and  filver,  which  has  been 
formerly  thrown  away  as  ufelefs,  and  is  now  collected 
by  women  and  children.  Befides  thefe  other  mat 
ters  are  added,  containing  lead  and  filver,  as  the  tells 
employed  in  refining,  the  drofs  of  lead,  impure  litharge, 
and  any  rubbifh  containing  metal,  which  was  left  in 
the  furnace  after  the  foregoing  fuficn.  All  thefe 
matters  being  mixed  together,  are  thrown  into  the 
furnace:  and  to  each  meafure  of  this  mixture  a  mea- 
fure  of  charcoal  is  added.  The  fufion  is  then  begun 
by  help  of  bellows  ;  and  as  it  proceed-,  the  lead  falls 
through  the  light  brafque  or  charcoal-bed  into  the 
hollow,  or  caile,  where  it  is  prefer ved  from  burning 
under  the  powder  of  charcoal.  The  fcoria,  on  the 
other  hand,  being  lighter  and  lefs  fluid,  is  fkimmed 
off  from  time  to  time  by  means  of  ladles,  that  it  may 
not  prevent  the  reft  of  the  lead  from  falling  down  in 
to  the  hollow.  Thus,  while  the  fufion  lafts,  frefli  mat 
ters  and  freih  charcoal  are  alternately  added,  till  the 
whole  quantity  intended  for  one  fufion,  cr  as  they  call 
it,  one  dr.y-t  be  thrown  in. 

There  are  feveral  eflential  things  to  be  remarked  in 
this  operation  which  is  very  well  contrived.  Firft, 
The  mixture  of  matters  from  which  a  little  lead  and 
filver  is  procured,  which  would  otherwife  be  loft  ;  and 
which  have  a]fo  this  advantage,  that  they  retard  the, 

fufioa 


t    464    3 

fufion  of  the  RanicKberg  ore,  which,  however  "well 
roafted  it  has  been,  retains  always  enough  of  the  inl- 
phur  and  iron  of  the  pyrites  mixed  with  it,  to  rercU.r 
it  too  fufible  or  too  fluid  ;  fo  that  without  the  addi 
tion  of  thofe  matters  nothing  would  be  obtained  but 
a  matt.  It  is  even  nccetfary,  Hotwithftanding  thefe 
additions,  not  to  hatten  the  fufion  too  much,  but  to 
give  time  for  the  ore  to  mix  \vLh  other  matters,  elfe 
it  would  melt  and  flow  of  itfelf  before  the  reft.  Se 
condly,  The  fufion  of  the  ore  through  charcoal  which 
is  practifed  in  moft  fmelting-houfes,  and  for  almoft  all 
ores,  is  an  excellent  method,  the  principal  advantage 
of  which  is  the  faving  of  fuel.  The  action  of  the  burn 
ing  charcoal  dii  ecled  immediately  upon  the  mineral, 
at  the  fame  time  that  it  melts  it  more  readily  and  ern- 
cacioufly,  alfo  fupplies  it  with  the  phlogiftion  necef- 
faiy  to  bring  it  to  a  perfect  (late. 

From  the  Ramelfberg  ore  after  its  fir  ft  rowing  a 
white  vitriol  is  obtained  and  prepared  at  Goilar,  whole 
bafis  was  zinc :  which  proves  that  this  ore  contains 
alfo  a  certain  quantity  of  this  femimetal.  As  this  ore 
is  fmelted  in  a  country  where  the  art  is  well  understood 
of  extracting  every  thing  which  a  mineral  contains,  fo 
in  this  fufion  zinc  and  cadmia  are  obtained  in  the  fol 
lowing  manner  :  When  the  furnace  is  prepared  for  the 
fufion,  it  is  neceflary  to  clofe  it  up  in  the  fore-part  be 
fore  the  fufion  is  begun. 

"  Firft  of  all,  a  gritt-ftone  is  to  be  placed,  fupport- 
ed  at  the  height  of  three  inches.  This  (lone  is  as  long 
as  the  furnace  is  broad,  and  the  height  of  it  is  level 
with  the  hole  where  the  bellows-pipe  enters.  It  is 
fattened  to  each  fide  of  the  furnace,  externally  and  in 
ternally  with  clay.  Upon  this  (lone  a  kind  of  re 
ceptacle,  or,  as  it  is  called,  \htfeat  of  lie  tine,  is  made 
in  the  following  manner  :  A  flat  flaty  ftone  is  chofen 
as  long  as  the  furnace  is  broad,  and  eight  inches  in 
breadth.  This  is  placed  on  the  gritt-ftone  aboverncn- 
tioned,  in  fuch  a  manner  that  it  inclines  conMerably 

r  toward* 


towards  the  front  of  the  furnace,  and  that  its  bottom 
touches  clofely  the  gritt  ilone.  It  is  fattened  with 
clay,  which  is  alfo  laid  upon  the  feat  of  the  zinc. 
Upon  this  feat,  which  is  to  receive  the  zinc,  two  round 
pieces  of  charcoal  are  placed,  and  alfo  a  ilone  called 
the  Kincjlon0)  which  is  about  a  foot  and  an  a  half  in 
length,  and  clofes  one  part  of  the  front  of  the  fur 
nace.  This  ttone  alfo  is  fattened  on  each  of  its  fides 
with  clay.  Clay  is  likewife  put  under  the  ftone  be 
twixt  the  two  pieces  of  charcoal,  which  hinder  it  from 
touching  the  ieat  of  the  zinc.  The  m-ider-part  of  this, 
itone  is  but  (lightly  luted,  that  the  workmen  may 
make  an  opening  for  the  zinc  to  flow  out.  This  is 
made  the  feat  or  receptacle  of  the  zinc  to  detain  this 
metallic  fubttance,  which  would  otherwife  fall  into  the 
hotteft  part  of  the  fire,  called  by  the  workmen  the 
mating  place,  and  would  be  there  burnt,  whereas  it  is 
collected  upon  this  receptacle  during  the  fufion,  where 
it  is  Iheltered  from  the  action  of  the  bellows,  and  con- 
iequcntly  from  too  great  heat. 

"  When  all  the  matter  to  be  fufed  in  one  day  is 
put  into  the  furnace,  the  blaft  of  air  is  continued  till 
that  matter  has  funk  down.  When  it  is  half  way 
down  the  furnace,  they  draw  out  the  fcoria,  that  more 
of  the  ore  and  other  matters  may  be  e \pofed  to  the 
greatett  heat.  As  foon  as  the  fcoria  is  cooled  aad 
fixed  a  little,  two  (hovel-fulls  of  fmall  wet  fcoria  or 
land  is  thrown  clofe  to  the  furnace,  and  beat  down 
with  the  lhovei ;  then  the  workmen  open  the  feat  or 
receptacle  of  zinc,  and  ftrike  upon  the  zinc-ftone  to 
make  the  femimetal  flow  out  As  foon  as  the  pure'tt 
part  of  it  has  flowed  out,  it  is  fprinkled  with  water 
aud  carried  away.  Then  the  workmen  feparate  en 
tirely  the  zinc-ftone  from  the  wall  of  the  furnace,  and 
they  continue  to  give  it  little  ftrokes,  that  the  fmail 
particles  of  zinc  difpcrfed  among^the  charcoal  by  an  iron 
fall  down.  This  being  done,  the  ftone  is  removed  ; 
and  the  zinc  is  feparated  from  the  charcoal  by  an  iron 

inftruxnent, 


inftrument,  is  cleaned,  and  remelted  along  with  the 
zinc  that  flowed  out  at  fir  ft,  and  is  call  into  round 
cakes.  The  reafon  why  the  zinc  is  withdrawn  before 
the  bellows  ceafe  to  blow,  is,  that  if  it  was  left  till  the 
charcoal  on  the  feat  or  receptacle  was  confirmed,  it 
would  be  rnoflly  burnt,  and  little  would  be  obtained. 
Thus  after  the  vine  is  withdrawn,  the  fufion  is  finiihcd 
by  blowing  the  bellows  till  the  end." 

Thus  the  zinc  is  feparated  frcm  the  ore  of  Ra- 
melfberg,  and  is  not  confounded  in  the  hollow  or 
caiTe  with  the  lead  and  filver,  becaufe,  being  a  volatile 
femimetal,  it  cannot  fupport  the  activity  of  the  fire 
without  rifmg  into  vapours,  which  are  condenfed  in 
the  place  leail  hot,  that  is  to  fay,  upon  the  (rones  ex- 
prefsly  prepared  for  that  purpofe  ;  and  which,  being 
much  thinner  than  the  other  walls  of  the  furnace,  are 
continually  cooled  by  the  external  air. 

It  is  alfo  in  this  furnace,  and  after  the  fufion  of 
the  Ramellberg  ore,  that  the  cadmia  of  zinc,  or  the 
cadmia  of  furnaces ,  is  obtained.  -This  ore  is  com- 
pofed  of  fulphureous  and  ferruginous  pyrites  of  true 
lead-ore  containing  filver,  and  a  very  hard  and  com- 
pacl  matter  of  a  dark  brownifh-grey  colour,  which  is 
probably  a  lapis  calammaris,  or  an  ore  of /inc.  Thefe 
feveral  matters  of  the  Ramelfberg  ore  are  not  fepa 
rated  from  each  other,  either  for  the  roafting  or  for 
the  fufion.  Thus  there  is  zinc  in  all  the  parts  of  the 
roafted  ore  ;  and  much  more  of  it  would  be  obtained^ 
if  it  was  not  fo  ealily  infl ammable.  All  the  zinc 
which  is  obtained  is  preferved  from  burning  by  falling, 
while  in  fufion,  behind  the  chcmife  or  fore-part  of  the 
furnace,  which  is,  as  has  been  faid,  a  kind  of  fchiftus 
or  (late,  called  by  the  workmen  feel-fans.  But  the 
part  of  this  femimetal  which  falls  in  the  middle  of  the 
furnace,  near  the  middle-wall,  or  towards  the  fides, 
being  expofed  to  the  greateft  heat  of  the  fire,  is  there 
burnt ;  and  its  fmoke  or  flowers  attaching  itfelf  on  all 
fides  to  the  walls  of  the  furnace,  undergo  there  afemi- 

fufion, 

2 


I     4<57     ] 

fuiion,  which  renders  this  matter  fo  hard  and  fo  thick, 
that  it  mud  be  taken  away  after  every  fourth  fufion, 
or,  at  moil,  after  every  fixth  fuiion.  That  which  is 
found  attached  to  the  higheit  part  of  the  furnace  is 
the  bed  and  pureft.  The  reft  is  altered  by  a  mixtare 
of  a  portion  of  lead  which  it  ha?  carried  up  with  it ; 
and  which,  from  its  great  weight  and  fixity,  h.is  hin 
dered  the  zinc  from  riling  fo  high  as  it  would  have 
done  alone.  Therefore,  with  this  kind  of  impure 
cadmia,  ductile  biafs  cannot  be  made. 

Almoft  all  the  zinc  we  have,  as  well  as  the  cadmia 
of  the  furnaces,  is  obtained  from  the  RameKberg  ore 
by  the  procefs  defcribed,  and  coniequently  is  nut  the 
produce  of  a  pure  ore  of  zinc  or  -lapis  ca'amniaris^ 
which  is  never  fufed  for  that  purpofe.  Belore  Mr 
Margraaf,  although  it  "was  well  known  that  this  ore 
contained  zinc,  and  that  it  was  employed  for  the 
making  of  brafs,  a  convenient  proc'jfs  fur  extracting 
zinc  from  it  was  not  known  ;  becaufe,  when  treated 
by  fuiion  with  fluxes,  like  other  ores,  it  does  not 
yield  any  zinc  :  which  proceeds  partly  from  the  re 
fractory  quality  of  the  earth  contained  in  the  calamine, 
that  cannot  be  fufed  without  a  very  violent  fire  ; 
and  alfo  from  the  volatility  and  comlmfubility  of  the 
zinc,  which  for  this  reafon  cannot  be  collected  at  the 
bottom  of  a  crucible,  as  a  regulus  under  a  fcoria,  like 
moil  metals. 

M.  Margraaf  has  remedied  thefe  inconveniences  by 
di  frilling /#&>  calam'marh^  mixed  with  charcoal,  in  are- 
tort,  to  which  is  joined  a  receiver  containing  ibme  wa 
ter,  and  coniequently  in  clofe  vcilels,  where  the  zinc, 
by  the  help  of  a  very  ftiong  fire  indeed,  is  fublimcd  in 
its  metallic  form  without  burning.  lie  alfo  by  the  fame 
method  reduced  into  zinc  the  flowers  of  z'nc,  o>r  pom- 
phol'ix,  cadmia  of  th.'  furnace ;  tuily>  which  is  alfo  a 
kind  of  cadmia  ;  in  a  word,  all  matters  capable  of 
producing  zinc  by  combination  with  phlogifton. — 
But  it  is  evident  that  i\n.h  operations  as  thefe  are  ra- 

ther 


[     463     ] 

tlier  tit  to  fupply  proofs  for  chemical  theory,  than  to 
be  put  in  pra&ice  for  works  in  great.  M.  Margraaf 
kas  obferved,  that  the  zinc  which  he  obtained  by  this 
procefs  was  leis  brittle  than  what  is  obtained  from  the 
fufion  of  ores;  which  may  proceed  from  its  greater  pu 
rity,  or  from  its  better  combination  with  phlogillon. 

Zinc  is  obtained,  not  only  in  the  method  ufed  at 
Collar  above  defcribed  ;  but  is  alfo  extracted  in  great 
works,  from  lapis  caLmlnarh  and  calcine,!  blend,  by  a 
di  filiation  fimilar  to  that  by  which  M.  Margraaf  has 
elfayed  ores  of  zinc.  The  firit  work  of  that  kind 
was  erected  in  Sweden  by  Mr  Von  Swab,  in  the  year 
1738.  The  ore  employed  was  a  kind  of  blend  ;  this 
ore,  when  calcined,  powdered,  and  mixed  with  char 
coal,  was  put  into  iron  or  Hone  retorts,  and  the  zinc 
was  obtained  by  diftillation.  In  Briitol  a  work  is 
eftabliihed  in  which  zinc  is  obtained  by  diftiilation  ly 
*jhrt 

Alter  this  digreffion  which  we  have  now  made  con 
cerning  the  operation  in  th-  great  by  which  zinc  and 
cadmia.  are  obtained,  and  which  we  could  not  infert 
olfewhere,  becaufe  of  the  neceifary  relation  it  has  with 
the  fmelting  of  the  Ivameliberg  ore,  we  proceed  to 
The  other  operations  of  the  fame  ore  ;  that  is  to  fay, 
to  thtj&WRry,  by  which  the  iilver  is  fcpa  rated  from  the 
lead,  which  are  mixed  together,  forming  what  is  called 


This  operation  differs  from  tl\Q  faing  of  ejay^  or  in 
i/,  principally  in  this  circtim  fiance,  that  in  the  latter 
method  of  lining  all  the  litharge  is  ab.'orbed  into  the 
cupel,  whereas  in  the  former  method  the  grcateit  part 
of  this  litharge  is  withdrawn. 

The  fining  in  great  of  the  work  of  Rame!il>erg  is 
performed  in  a  iurnaco  called  a  rev:rle.'atvry  furnace. 
This  furnace  is  fo  contlnifted  that  the  ilamc  of  wood 
burning  in  a  cavity  caUcd  tliej^Y-^/,//-,  is  determined 
by  a  current  of  air  (which  is  introduced  through  the 
afb-holc,  and  wliicli  goes  (.ait  at  an  opening  on  one  fide 


of  that  part  of  the  furnace  where  the  work  is,  that  is, 
where  the  lead  and  liiverare)  to  circulate  above,  and 
to  give  the  convenient  degree  of  heat,  when  the  fire  is 
properly  managed._  In  this  furnace  a  great  cupel,  call- 
ed  a  teft,  is  difpofed.  This  teft  is  made  of  the  aihes  of 
beech-wood,  well  lixivated  in  the  ufual  manner.  In 
fame  founderies  different  matters  arc  added,  as  fand, 
fp.rr,  calcined  gypfum,  quicklime,  cluy.  When  thj 
teft  is  well  prep. ired  and  dried,  all  the  work  is  put  at 
once  upon  the  cold  telt,  to  the  quantity  of  64  quin 
tals  for  one  operation.  Then  the  fire  is  lighted  in  the 
fire -place  with  faggots  j  but  the  fufion  is  not  urged  too 
faft,  i.  That  the  teft  may  have  time  to  dry;  2.-Y>c- 
caufe  the  work  of  the  Ramelfberg  ore  is  allayed  by  the 
mixture  of  feveral  metallic  matters,  which  it  is  proper 
to  feparate  from  if,  otherwife  they  would  fpoil  the  li 
tharge  and  the  lead  procured  from  it.  Thefe  metallic 
matters  are,  copper,  iron,  zinc,  and  matt.  As  thsfe 
heterogeneous  fubftances  are  hard  and  refractory,  they 
do  not  melt  fo  foon  as  the  work,  that  is,  as  the  lead 
and  filver :  and  when  the  work  is  melted,  they  fwim 
upon  its  furface  like  a  fkin,  which  is  to  be  taken  off. 
Thefe  impurities  are  called  the  fcum  or  the jfirft-nuafc. 
What  remains  forms  a  fecond  fcum,  which  appears 
when  the  work  is  at  its  greateft  degree  of  heat,  but 
b -fore  the  litharge  begins  to  form  itfelf.  It  is  a  fcoria 
which  is  to  be  carefully  taken  oiF.  It  is  called  the 
fecond  ivajle. 

When  ths  operation  is  at  this  point,  it  is  continued 
by  the  help  of  bellows,  the  wind  of  which  is  directed, 
not  upon  the  wood  or  fuel,  but  upon  the  very  furface 
of  the  metal,  by  means  of  iron-plates  put  for  that  pur- 
pofe  before  the  blaft-hole,  which  are  called  papilkm. 
This  blafl  does  not  fo  much  increafe  the  intsnfity  of 
the  fire,  as  it  facilitates  the  combuftion  of  the  lead, 
and  throws  the  litharge  that  is  not  imbibed  by  the  tefl  > 
towards  a  channel,  called  the  litharge-way^  through 
which  it  flows.  The  litharge  becomes  fixed  out  of  the 

2  furnace :, 


L     47°     J 

•furnace  :  the  matter  which  is  found  in  the  middle  of 
the  largeit  pieces,  and  which  amounts  to  about  a  half 
or  a  third  of  the  whole,  is  friable,  and  falls  into  pow 
der  like  fand.  This  is  put  into  barrels  containing  each 
five  quintals  of  it ;  and  is  called  faleallt  litharge,  be- 
t  a ule  it  is  fold  in  that  ftate.  The  other  part,  which 
remains  folid,  is  called  cold  litharge,  and  is  again  melted 
arid  reduced  into  lead,  The  fuiion  is  called  cold  fu- 
J:oi,  and  the  lead  obtained  from  it  cold  bad,  which  is 
good  and  fal  cable  when  the  work  has  been  well  clear 
ed  from  the  hetercgenous  matters  mentioned  above. 
The  tefts  and  cupels  impregnated  with  litharge  are 
added  in  the  fufion  cf  the  ore,  as  we  have  already  re 
lated. 

When  two-thirds,  cr  nearly  that  quantity,  of  the 
lead  are  converted!  into  litharge,  no  more  of  it  is 
i'oimed.  The  filver  then  appears  covered  with  a  white 
ikin,  which  the  finers  call  lighlenm^  and  the  metal 
i'ght:nc'd  or  fined Jifaer. 

The  iilver  obtained  by  this  procefs  of  fining  is  not 
yet  altogether  pure.  It  ftill  contains  feme  lead,  fre 
quently  to  the  quantity  of  four  drams  in  each  marc 
or  eight  cunces.  It  is  delivered  to  the  workmen,  who 
complete  its  purification  by  the  ordinary  method. 
This  laft  operation  is  the  refining-,  and  the  workmen 
employed  to  do  it  are  called  n-fners.  A  fining  of  64 
quintals  of  work,  yields  from  8  to  10  merks  cf  fined 
Iilver,  and  from  35  to  40  quintals  of  litharge  ;  that  is 
from  12  to  1 8  of  faleable  .litharge,  firm  22  to  23  of 
cold  litharge,  from  20  to  22  quintals  of  impregnated 
teft,  and  from  6  to  7  quintals  of  lead-drois.  The  ope 
ration  lafts  from  i^  to  18  hours. 

§  2.  Ores  containing  iilver  may  be  divided  into  four 
kinds,  i.  Pure,  or  thofe  which  are  rot  much  com 
pounded  with  other  metalf.  2.  Galenical,  in  which 
the  filver  is  mixed  with  much  galena,  or  ore  of  lead 
rr  ineralifed  by  fulphur.  3.  Pyritous,  in  which  the 
fijver  is  mixed  with  the  martial  pyrites.  4.  Cupreous, 

In 


C    471    1 

in  which  the  filler  is  contained  in  copper  ores.  To- 
extract  the  filver  from  thefe  feveral  kinds  of  ores,  diffe 
rent  operations  are  neceffary. 

Native  filver  is  feparated  from  its  adhering  earths 
and  f  tones,  by  amalgamation  with  mercury  in  the  man 
ner  directed  for  the  reparation  of  gold;  or  by  fufion 
"with  lead,  from  which  it  may  be  afterwards  feparated 
by  cupeiiation. 

Pure  oresfeldom  require  a  previous  calcination  ;  but 
when  bruiied  and  cleanfed  from  extraneous  matters,, 
may  be  fufed  directly,  and  incorporated  with  a  quan 
tity  of  lead  ;  unlefs  they  contain  a  large  proportion, 
of  fulphur  and  arfenic,  in  which  cafe  a  calcination 
may  be  ufeful.  The  lead  employed  mud  be  in  a  cal 
cined  or  vitrified  ftate,  which  being  mixed  with  the 
ore,  and  gradually  reduced  by  the  phlcgiftion  of  the 
charcoal  added  to  it,  may  be  more  effectually  united  , 
with  the  fiver  of  the  ore,  than  if  lead  itfelf  had  been 
added,  which  would  too  quickly  precipitate  to  the 
bottom  of  the  containing  velfel  or  furnace.  The  fil 
ver  is  to  be  aiterwards  feparated  from  the  lead  by  cu- 
peJiUtion* 

Galenical  ores,  especially  thofe  in  which  pyrites  is 
intermixed,  require  a  calcination,  which  ought  to  be 
performed  in  an  oven,  orreverberatoiy  furnace.  They 
are  then  to  be  fufed  together  v/ith  feme  inflammable 
matter,  as  charcoal,  by  which  the  lead  is  revived,  and 
together  with  the  filver  is  precipitated. 

Pyritous  ores  muit  be  firft  melted,  fo  as  to  form  a 
matt.  If  the  fulphur  is  not  furncient  for  this  kind  of 
fufion,  more  fulphurated  pyrites  may  be  added.  This 
matt  contains,  befides  filver  and  fulphur,  alfo  various 
metals,  PS  lead,  iron,  and  fomettrnes  cobalt.  The 
matt  mull  be  expofed  to  repeated  calcination  till  ilu- 
fulphur  h  diffipated.  By  thefe  calcinations  moft  of 
the  iron  is  destroyed.  The  calcined  matt  is  to  be  fu 
fed  with  litharge,  and  the  filver  incorporated  with  the 
revived  le^d  ;  with  which,  and  from  the  ether  imper*. 
Qjq  3,  feel: 


C    47*    ]: 

f«<5l  metals  with  which  it  may  be  mixed,  it  mutt  after 
wards  be  feparated  by  cupellaticn. 

The  filver  contained  in  cupreous  ores  may  be  ob 
tained,  either,  i.  By  feparating  it  from  the  copper 
itfelf,  after  this  has  been  extracted  along  with  the  filver 
in  the  uiual  manner,  from  the  ore;  or,  2.  By  pre 
cipitating  it  immediately  from  the  other  matters  of 
the  ore. 

1.  It  may  be  feparated  from  the  copper  by  two  me 
thods.      One  of  thefe  is  by  adding  lead,  and  fcorifying 
the    imperfect  metals.      By  this  method  much  of  the 
copper  \vould  be  deftroyed,  and  it  is  therefore  not  to 
be.ufed  unleis  the  quantity  of  filver  relatively  to  the 
copper  be  considerable.     Another  method  by  which 
Jilver  may  be  feparated  from  copper  is  by  eliquation  ;. 
that  is,  by  mixing  the  mafs  of  copper  and  filver  wi<h 
a  quantity  of  lead,  and  applying  inch  a  heat  as  ftiall 
be  juft  fufticient  to  make  the  lead  eliquate  from  the 
copper,  together  with  the  I'ilver,  which  being  more 
iirongly  dilpofed  to  unite  with  the  lead  than  with  the 
copper,  is  thus  incorporated  with  the  former  metal, 
und  feparated  from  the  latter. 

2.  Silver  may  alfo  be  extracted  from  thefe  cupreous 
ores  by  precipitation.     For  this  purpofe,  let  the  ore, 
previouily  bruifed  and  cleanfed,  be  formed  into  a  matt 
that  the  earthy  mater  may  be   well  feparated.     Let 
the  matt  be  then  fufed  with  a  flrongheat ;  and  when 
the  fcoria  has  been  removed,  and  the  heat  is  dimi- 
niilied,    add    to  it  feme  clean  galena,  litharge,  and 
granulated  lead.    When  the  fire  has  been  railed,  and 
the  additions  well  incorporated  with  the  matt,  let  fome 
caft  or  filed  iron  be  thrown  into  the  liquid  rnafs,  which 
being  more  difpofed  than  lead  is  to  unite  with  ful- 
phur  will  feparate  and  precipitate  the  latter  metal, 
and  along  with  it  the  filver  or  gold  contained  in  the 
matt.     This  method  wras  introduced  by  Scheffer,  and 
is  pracYiied  at  Adelfors  in  Smrland.    In  this  work  the 
proportion  of  the  feveral  materials  is,  four  quintals.of 

matt* 


[     473     ] 

matt,  two  quintals  of  black  copper  containing  ibme 
lead  with  the  perfect  rneta1,  one  quintal  of  galena, 
one  quintal  of  lidiarge,  a  fifth  part  of  a  quintal  of  gra 
nulated  lead,  and  an  equal  quantity  of  caft  iron. 

The  filver  in  this,  and  in  all  other  inftances  where  it 
is  united  with  lead,  is  to  be  afterwards  feparated  from 
the  lead  by  cupellation  :  which  procefs  is  defcribed 
at  the  articles  ESSAY  of  t'm  Value  of  Silver,  and  RE 
FINING. 


S  E  c  T  .  I V.      Sine  king  of  Ores  of  Copper. 

§  i.  THE  fmelting  in  great  of  copper  ores,  and  even 
of  feveral  ores  of  filver  and  lead,  excepting  that  of  Ra- 
rnelfberg,  is  performed  in  furnaces  not  eiientially  dif 
ferent  from  that  already  defcribed ;  but  in  this  refpeft 
oniy,  that  the  fccria  and  metal  are  not  drawn  out  of 
the  furnace,  but  flow  fpontaneouily,  as  foon  as  they 
are  melted,  into  receiving  bafons,  where  the  metal  is 
freed  from  the  fcoria.  Thefe  furnaces  are  generally 
called p':erced  furnaces. 

Infte  ul  of  a  light  brafque,  or  bed  cf  charcoal  pow 
der,  under  which  the  metal  lies  hid,  the  bottom  of 
thefe  furnaces  is  covered  with  a  baion  compofed  of 
heavy  brafque,  which  is  a  mixture  of  charcoal-powder 
and  clay.  In  the  front  of  the  furnace,  and  at  the 
bottom  of  the  chemife,  there  is  a  hole,  called  the  eye, 
through  which  the  melted  matter  flows  and  runs 
along  a  trench  or  furrow,  called  the  trace,  into  one 
or  more  receiving  ba'ons  made  of  earth,  fcoria,  fand, 
&c.  There  the  metal  is  feparated  from  the  fcoria, 
by  making  it  flow  from  theie  bafons  into  another  la 
teral  one.  Thefe  furnaces  alfo  are  called  crooked 
furnaces. 

Different  names  are  given  to  them  according  to  feme 
difference  in  their  conllruclion.  For  inftance,  thole 
which  have  two  eyes,  and  two  traces,  through  which 
the  melted  matter  flows  alternately  into  two  bafons,. 

are 


C     474     ] 

nre  called  fpecla de-furnaces.  Their  greater  or  lefs 
height  gives  occafion  alib  to  the  diftinction  of  high  fur 
naces  and  middle  furnaces. 

The  high  furnaces  are  of  modern  invention.  They 
were  firft  introduced  at  Mansfield  in  the  year  1727  ; 
and  the}7"  are  now  ufed  in  almoit  all  countries  where 
ores  are  fmelted,  as  in  Saxony,  Bohemia,  Hungary, 
ccc.  Their  chief  advantage  confilts  in  fimplirying 
and  diminiihing  the  labour.  This  advantage  is  effec 
ted  by  the  great  height  of  the  furnace,  which  allows 
the  ore  to  remain  there  a  long  time  before  it  falls  down 
into  the  hotteft  part  of  the  rlie  and  is  melted.  Con- 
fequently,  it  flitters  fucceilively  different  degrees  of 
heat;  and,  before  it  is  melted,  it  undergoes  a  road- 
ing  which  cofts  nothing  ;  therefore  the  high  furnaces 
are  chiefly  employed  for  crude  fufions ;  and  particu 
larly  for  the  flate  copper  ore.  Thefe  furnaces  are 
above  18  feet  high.  A  too  great  height  is  attended 
with  an  inconvenience,  befides  the  trouble  of  fuppiy- 
ing  it  with  ore  and  fuel,  which  is,  that  the  charcoal  is 
moilly  confumed  before  it  gets  down  where  the  greatett 
'  heat  is  required,  and  is  then  rendered  incapable  of 
maintaining  a  fire  fufficiently  intenfe. 

All  the  furnaces  which  we  have  mentioned  are 
fnpplied  with  large  bellows,  moved  by  the  arbor  of 
a  wheel,  which  is  turned  round  by  a  current  of 
water. 

The  only  kind  of  furnace  for  fm citing  ores  where 
bellows  are  not  employed,  is  what  is  called  a  rever- 
bratory  furnace.  The  Germans  call  it  a  wind  fin  • 
nace.  it  is  alfo  diftinguifhed  by  the  name  of  Englijb 
furnace,  becaufe  the  invention  of  it  is  attributed  to  an 
Englifh  phyfician  of  the  name  of  Wright ,  who  was 
well  verfed  in  chemiftry  ;  and  becaufe  the  ufe  of  it 
was  firft  introduced  in  England  about  the  end  of 
the  Lift  century,  where  it  is  much  employed,  as  well 
«\s  in  feveral  other  countries,  as  at  Konigfberg,  in 
Norway,  The 


L     475     3 

.  The  length  of  thefe  furnaces  is  about  18  feet,  com- 
prehending  the  mafonry  :  their  breadth  is  i  2  feet,  and 
their  height  nine  feet  and  a  half.  The  hearth  is  raifed 
three  fe^t  above  the  level  of  the  found  cry  ;  on  one  fide 
is  the  fire  place,  under  which  is  an  ain-hole  hollowed 
in  the  earth  ;  on  the  ether  fide  is  a  bafon  made,  which 
i?  kept  covered  with  fire  when  there  is  occafion :  on 
the  anterior  fide  of  this  furnace  there  is  a  chimney, 
\vhich  receives  the  flame  after  -it  lias  pailed  over  the 
mineral  that  is  laid  upon  the  hearth.  This  hearth, 
which  is  in  the  interior  part  of  the  furnace,  is  made  of 
a  clay  capable  of  fuftaining  the  fire.  The  advantage 
of  this  furnace  is,  that  bellows  are  not  neceflary  ;  and 
confequen'ly  it  may  be  conftiucled  where  there  is  no 
current  of  water,  and  wherever  the  mine  happens  to 
be.  This  furnace  has  a  hole  in  its  front,  through 
which  the  fcoria  is  drawn  out ;  and  a  bafon,  as  we 
have  faid,  on  one  fide,  made  \\i;h  find,  in  which 
are  oblong  traces  for  the  reception  of  the  matt,  and 
of  the  black  copper,  when  they  flow  out  of  the  fur 
nace. 

Copper  is  generally  m'neralifed,  not  only  by  ful- 
pliur  and  arfenic,  but  alfo  by  fjmimetals  and  nyiitous 
matters,  and  is  frequently  mixed  with  ether  motals. 
As  this  metal  has  great  affir.ity  with  fulphur  and  ar- 
fenicj  it  is  a! moil  impoffible  to  difengagc  it  from  them 
entirely  by  roafting:  hence,  in  the  fmelting  in  great 
nothing  is  obtained  by  the  firil  operation  but  a  copper, 
matt,  which  contains  all  the  principles  of  the  ore, .ex 
cepting  the  earthy  and  irony  parts,  particularly  when 
the  ore  is  irnelted  crude  and  unroafted.  Afterwards 
this  matt  mull  be  again  rcafted  and  fufed.  The  pro 
duce  of  this  fdcond  fufion  begins  Hill  more  to  refemble 
copper^  but  is  not  malleable.  It  continues  mixed 
with  almoft  all  the  minerals,  particularly  with  the  me- 
tivs.  As  it  is  frequently  of  a  black  colour,  it  is  always 
called  Hack  cc-ppery  when  it  is  unmalleable,  whatever 
its  cokur  happens-  really  to  bs. 

As. 


C    476    ] 

As,  of  all  the  imperfect  metals,  copper  is  mod 
ficultly  burnt  and  fcorified,  it  is  again  remelted  fcveral 
times,  in  order  to  burn  and  fcorify  the  metallic  fab- 
ftances  mixed  with  it;  and  this  is  done  till  the  cop 
per  is  perfectly  pure,  which  is  then  called  red  or  rc- 
fned  copper )  and  thefe  laft  fufions  are  called  ihzfnir.g 
arid  refining  of  it :  red  copper  contains  no  metals  but 
gold  and  filver,  if  any  of  thefe  happened  to  be  in 
the  ore. 

In  order  to  avoid  all  thefe  fufioi-.s,  it  has  b:en  pro- 
pofed  to  treat  in  the  humid  way  certain  copper  ores, 
particularly  thofe  which  are  very  pyritous.  This  method 
confifts  in  making  the  blue  vitriol  from  the  ore,  by 
roafling  and  lixiviating  it,  and  in  precipitating  pure 
copper  from  this  lixivium,  which  is  called  cement- 
wafer,  by  means  of  iron  :  but  it  is  not  much  prac- 
t'fed,  becaufe  it  has  been  obferved,  that  all  the  cop 
per  contained  in  the  ore  was  not  procured  by  this 
means. 

As  expence  is  not  much  regarded  in  fmall  eflays 
and  experiments,  thefe  fufions  are  much  abridged  and 
facilitated  by  adding  at  firft  faline  and  glaffy  fluxes  ; 
and  then  by  refining  the  black  copper  with  lead  in 
the  cupel,  as  gold  and  filver  are  done.  In  this  me 
thod  of  refining,  it  is  to  be  moft  carefully  obferved, 
that  the  metal  be  fufed  as  quickly  as  podible,  and 
expofed  to  no  more  heat  than  is  neceiTary,  left  it  be 
calcined. 

When  the  black  copper  contains  forne  iron,  but  not 
a  great  deal,  the  lead  prefently  feparates  the  iron  from 
it,  and  makes  it  rife  to  the  furface  of  the  copper :  but 
if  the  iron  be  in  too  large  a  proportion,  it  prevents  the 
lead  from  uniting  with  the  copper.  Thefe  two  phe 
nomena  depend  on  the  fame  caufe,  which  is,  that 
lead  and  iron  unite. 

Frequently  copper  ores  contain  alfo  a  quantity  of 
filver  fufficient  to  make  its  extraction  by  particular 
proceifes  profitable.  It  was  long  before  any  prc- 

cefs 


[     477     3 

ccis  could  be  thought  of  for  this  purpofe  which  was 
not  too  expeniive  and  troublefome  :  but  at  length 
it  is  accompiilhed  by  the  excellent  operation  called 
e  "iquation* 

The  copper  from  which  filver  has  been  feparated  by 
eliquatien  muft  be  refined  after  this  operation,  as  it  is 
generally  black  copper  from  which  filver  is  extracted  : 
but  even  if  it  had  not  been  black  copper  which  was 
employed  for  this  operation,  it  would  require  to  be 
refilled  on  account  of  a  little  lead  it  always  retains.  It 
is  therefore  carried  to  the  refiner's  furnace,  when  this 
operation  is  performeed  by  help  of  bellows,  the  blall  of 
which  is  thrown  upon  the  furface  of  the  melted  me 
tal.  As  in  this  refining  of  copper  the  precife  time 
when  it  becomes  pure  cannot  be  known,  b;:caufe  fcoria 
is  always  formed  on  its  furvace,  it  js  ncceilary  to  ufe 
an  eif.iy-ircn,  the  poliihed  end  of.  which  .being  dipt  in 
melted  cof>per»lhows  that  this  met.il  i>  pare  when  the 
copper  adhei  ing  to  the  iron  falls  oiFas  foon  as  it  is  dipt 
ia  cold  wacer. 

Wlicn  this  mark  of  the  purity  of  the  copper  has 
been  obferved,  its  furface  ought  to  b2  well  cleaned  ; 
and  as  loon  as  k  begins  to  lix,  it  mufi  be  fprinkkd 
with  a  broom  or  befom  dipped  in  cold  water.  The  fur- 
face  of  the  copper  which  is  then  fixing,  being  iuddqn- 
ly  cooled  by  the  water,  detaches  itfelf  from  the  reft  of 
the  metal,  is  taken  hold  of  by  tongs,  and  is  thrown 
red  hot  into  cold  water.  By  again  fprinkling  water 
on  the  m.ifs  of  copper,  it  is  all  of  it  reduced  into  plates 
which  are  called  rcfe&eti  and  thsfe  plates  are  what  is 
culled  rofette-copp:r. 

§  2.  The  copper  of  pyritous  cupreous  ore  cannot  be 
obtained  without  feverul  operations,  which  vary  accord 
ing  to  the  nature  of  the  ores.  Thefe  operations  are 
(  hiefly  readings  and  fufions.  By  the  firlt  luiion  a  matt 
ij  produced,  which  is  afterwards  to  be  roalled  ;  and 
1'iitis  the  fu'ioTss  'iiid  r>a Rings  :re  to  be  alternately  ap 
plied,  till  by  the  kill  fufion  copper  is  obtained.  Thefe 

methods 


t  478   j 

methods  of  treating  pyritous  copper  ores  depend 
on  the  two  following  facts:  i.  Sulphur  is  more  dif- 
pofed  to  unite  with  iron  than  with  copper.  2.  The 
iron  of  thefe  ores  is  deductible  by  the  burning 
fulphur  during  the  reading  of  the  fuiion  of  the  ores, 
while  the  copper  is  not  injured.  This  fact  appears 
from  experiments  mentioned  by  Scheffer  and  by 
Wallerius,  and  fiom  the  daily  practice  of  fmelting  cu- 
perous  ores. 

From  thefe  facts  we  learn,  i.  That  fulphur  maybe 
employed  to  feparate  and  deilroy  iron  mixed  with  cop 
per.  2.  That  iron  may  be  employed  to  feparate  the 
fulphur  from  copper,  as  is  fometimes  done  in  the  ef- 
fay  of  fulphurated  copper  ores.  3.  That  by  adjuft- 
ing  the  proportion  of  the  iron  and  fulphur  to  each 
other  in  the  fm  citing  of  copper-ores,  thefe  two  fub- 
ftancesmaybe  made  to  deftroy  each  other,  and  to  pro 
cure  a  feparation  ot  the  copper  :  and  this  acljuftmcnt 
may  be  effected,  by  adding  fulphur  or  fulphureous  py 
rites  to  the  copper-ore,  when  the  quantity  of  fulphur 
contained  in  this  ore  relatively  to  the  iron  is  too 
fmall ;  or  by  adding  iron  when  the  fulphur  predo 
minates  ;  or  by  roaiting  by  which  the  Superfluous 
fulphur  may  be  expelled,  and  no  more  left  than  is 
fufEcient  for  the  deftructi -»n  of  the  iron  contained  in 
the  ore.  We  mail  apply  thefe  principles  to  the  follow 
ing  cafes. 

i.  When  the  quantity  of  fulphur  and  of  iron  in  a 
copper  ore  is  fmall,  and  efpecially  when  the  iruii  does 
not  too  much  abound,  a  previous  roafting  will  at  once 
calcine  the  iron,  and  expel  moft  of  the  fulphur;  fo  that 
by  one  fufion  the  calcined  iron  may  be  fcoriiied  and 
black  copper  may  be  obtained.  If  the  fulphur  has  not 
been  furliciently  expelled,  a  fecond  roafting  and  fufion 
aic  requiike  ;  for  the  whole  quantity  cf  fulphur  ought 
not  to  be  expelled  during  the  firil  roafting :  but  as 
much  ought  to  be  left  is  as  fufEcient  for  the  fcorifica- 
tion  of  the  calcined  iron  ;  other  wife  this  mij^t,  during 


C     479     ] 

the  fufian,  be  again  revived  and  united  with  the  cop 
per. 

2.  If,  in    a    copper    ore,  the  quantity  of  iron  be 
too  great,  relatively  to  the  fulphur,  fome  fulphurated 
pyrites,    efpecially   that  kind  which  contains  copper 
ought  to  be  added,  that  a  matt  may  be  obtained,  and 
that  the  iron  may  be  calcined  and  fcorified. 

3.  When  the  quantity  of  fulphur  and  iron  is  very 
great,  that  is,  when  the  ore  is  very  pyritous  and  poor, 
it  ought  to  be  fir  ft  formed  into  a  matt ;  by  which  it 
is    feparated    from    the  adherent  earths  and  ftones, 
and  the  bulk  is  diminifhed  ;  then    by    repeated    and 
alternate  readings  and  fuiions,  the  copper  may  be  ob 
tained. 

4.  When  the  quantity  of  fulphur  in  an  ore  is  great 
er  than  is  fufficient  for  the  forming  a  matt,  the  fuper- 
fluous  quantity  ought   to  be    previoufly   expelled  by 
roafting. 

The  copper  thus  at  firft  obtained  is  never  pure,  but 
is  generally  mixed  with  fulphur  or  with  iron.  It  is 
called  Hack  copper.  This  may  be  refined  in  furnaces, 
or  on  hearths. 

In  the  former  methods,  to  the  copper  when  melted  a 
fmall  quantity  of  lead  is  added,  which  unites  with  the 
fulphur,  and  is  fcoriiied  together  with  the  iron,  and 
floats  upon  the  furface  of  the  melted  copper,  This  pu 
rification  of  copper  by  means  of  lead  is  fimilar  to  the 
refining  of  filver  by  cupellation  ;  and  is  founded  on  the 
property  of  lead,  by  which  it  is  more  difpofed  to  unite 
with  fulphur  than  copper  is  ;  and  on  a  property  of 
copper,  by  which  it  is  lefs  liable  than  any  other 
imperfect  metal  to  be,  fcorified  by  lead.  But  as  c  p- 
per  is  alfo  capaple  of  being  fcoriiied  by  lead,  this 
operation  mull  be  longer  continued,  a: id  r.o  jr.oie 
lead  mil  ft  be  employed,  than  is  iufiicient  for  the  fe- 
paration  of  the  fulphur,  and  for  the  iccriricciticn  of  the 
iron. 

R  r  The' 


The  copper  might  alfo  be  purified  iro:n  rr.v 
ing  fulphur  by  adding  a  fufficient  quantity  of  iron  to 
engage  the  fulphur.  Thus  Mr  ScheiTer  found,  that  by 
adding  to  fclplmrated  copper  from  ,'wth  to  v'o.th  of  old 
caft  iron,  he  rendered  the  copper  pure  and  ductile.  See 
his  Difiertation  on  the  Parting  of  Metals  amongft  the 
SwcdiJJj  Memoirs  for  the  year  1752.  In  this  purifi 
cation,  the  quantity  ef  iron  added  ought  not  to  be  too 
little,  elfe  all  the  fulpliur  will  not  be  feparated ; 
and  it  ought  not  to  be  too  great,  elfe  the  fuperfluous 
quantity  will  unite  and  injure  the  purity  of  the  cop 
per.  The  fufion  and  fcorification,  with  additirn  of 
lead,  feems  to  be  the  beft  method  for  the  lad  purifica 
tion  of  copper. 

SECT.  V.    Smelling,  &c.  of  Ores  of  Iron. 

NOTWITHSTANDING  the  great  importance  of  this 
fubject,  and  the  labours  of  Reaurner,  Swedenborgius 
and  of  feme  authors,  we  have  ft  ill  a  very  im 
perfect  knowledge  of  the  caules  of  the  differences  of 
the  feveral  kinds  of  ores,  of  the  methods  of  fmclting 
beft  adapted  to  thefe  differences,  of  the  caufcs  cf  the 
good  and  bad  qualities  of  ditferent  kinds  of  iron, 
and  of  th?  means  of  fo  meliorating  this  metal,  that 
we  may  obtain  tough  and  ductile  iron  from  any  of 
its  ores. 

Swedenborgius  has  very  mduflrioufly  and  exactly 
defcribed  the  different  proceifes  now  uied  in  moft  parts 
of  Europe  for  the  fmclting  of  ores  cf  iron,  for  the 
forging  of  that  metal,  and  for  the  convcrfion  of  it  into 
out  we  do  not  find  that  he  or  any  other  anther 
have,  by  experiments  and  difcoveries',  contributed 
much  to. the  iiluftration  or  to  the  improvement  cf  this 
part  cf  metallurgy,  unlcfs,  perhaps,  we  except  thoi'e 
of  Mr  Reaumer,  concerning  the  loftening  cfcafl  iron 
by  cementation  with  earthy  fubftances. 

The 


The  ores  of  iron  are  known  to  vsiy  much  in  their 
appearance,  in  their  contents,  in  their  ck",:;rees  oi  iu- 
iibiiitv,  in  the  methods  neceflfary  i^rth-  e.UTaclion  of 
their  contained  metal,  and  in  the  qualities  of  the  mct.il 
when  extracted. 

Molt  ores  rcq  ::;:-  to  be  roamed  previ.v:f;y  to  their 
fufion  ;  fome  m  '^y,  and  <  ;  .  >  more 

violent  an.',  fire;    Thoi'j  v 

ta'n  much  Of  vitriolic 

long  c 

.  •;  kind  ii 

iruttovc,  L'oai  \  Swodiin  iron  is  laid  to  be  ob 

tained, 

Som?  ores  require  a  very  flight  reading  only, 
that  they  may  be  dried  and  rendered  friable. — 
Such  are  the  ores  called  log  ores,  and  others,  which 
being  in  a  calcined  ftate,  and  containing  little  ful- 
phureous  matter,  would,  by  a  farther  calcination,  be 
rendered  lels  capable  of  being  reduced  to  a  metallic 
ftate, 

The  roafting  of  ores  of  iron  is  performed  by  kind 
ling  piles,  confuting  offtrata  of  fuel  an ...  placed 
alternately  upon  one  another,  or  in  furnaces  iimiiar  to 
thofe  commonly  employed  for  the  calcination  of  limc- 
ftonei 

Some  authors  advife  the  addition  of  a  calcareous 
earth  to  fulpluueous  ores  during  the  roafting,  that  the 
falphur  may  be  abforbsd  by  this  earth  wlun  con 
verted  r.ito  quicklime.  But  we  may  obferve  that 
tho  quicklime  cannot  abforb  the  fulphur  or  fulphu- 
reous  acid,  till  thefe  be  iiric  extricated  from  the  ore, 
and  does  therefore  only  prevent  the  diffipation  of 
thefe  volatile  matters  ;  and,  fecondly,  that  the  ful 
phur  thus  united  with  the  quicklime  forms  a  hepar 
cf  fulphur,  which  will  unite  wTith  and  diMblve  the 
ore  during  its  fuiion,  and  prevent  the  precipitation  of 
the  metal. 

"  The  next  operation  is  \htfujion  or  fmelting  of  the 
ore.  This  is  generally  performed  in  furnaces  or 

towers, 


lowers,  from  20  to  30  feet  high  in  the  bottom  of 
which  is  a  bafon  for  the  reception  of  the  fluid  metal. 
Vv7hen  the  furnace  is  fufficiently  heated,  which  mtift  he 
done  at  fir  ft  very  gradually,  to  prevent  the  crack- 
ing  of  the  walls  ;  a  quantity  of  the  ore  is  to  he  thrown 
in,  from  time  to  time,  at  the  top  of  the  furnace  along 
with  a  certain  quantity  of  fuel  and  of  lime-dene,  or 
whatever  other  flux  is  employed.  When  the  fuel  be- 
iow  is  ccnfumed  by  the  tire  excited  by  the  wind  of 
ll»e  belknvs,  the  ore,  together  with  its  proportionable 
quantity  of  fuel  and  of  flux,  fink  gradually  down,  till 
•:y  are  expofed  to  the  greateft  heat  in  the  furnace. 
There  the  ore  and  the  flux  are  fufed,  the  metallic 
particles  are  revived  by  the  fuel,  are  precipitated 
by  means  of  th-::ir  weight  through  the  fcoria  formed 
of  the  lighter  earthy  parts  of  the  fiux  and  of  the 
ITC,  and  unite  in  the  bafon  at  the  bottom  of  the 
•furnace,  forming  a  mafs  of  fluid  metal  covered 
by  a  glal'fy  fcoria.  When  a  furricient  quantity  of 
liiis  fluid  metal  is  collected,  which  is  generally  twice 
cr  thrice  in  24  hours,  an  apertuie  is  made,  through 
Avhich  the  metal  flows  into  a  channel  or  groove  made 
in  a  bed  of  land  ;  and  from  thence  into  fmaller  lateral 
cr  connected  channels,  or  other  moulds.  There  it  is 
cooled,  becomes  folid,  and  retains  the  forms  of  the 
channels  cr  moulds  into  which  it  flows.  The  piece 
of  iron  fc .imed  in  the  large  channel  is  called  a  fiw 
and  thofe  i'bimed  in  the  fmaller  channels  are  called 
figs.  Sometimes  Lhe  flu:d  iron  is  taken  out  of  the  furnace 
by  means  of  ladles,  and  poured  into  moulds  ready  pre 
pared,  of  fand  or  of  clay,  and  is  thus  formed  into  the 
various  utenfils  and  inftruments  for  which  caft  ircn  is  a 
proper  material. 

The  fcoria  mutt  be,  from  tirre  to  time,  allowed  to 
flow  cut,  when  a  conilderr.bic  quantity  of  it  is  formed 
through  an  aperture  made  in  the  front  of  the  furnace 
for  that  purpof  j.  A  fufficient  quantity  of  it  mint, 
however,  be  always  left  to  cover  the  furface  of  thq 
nielted  iron,  elfe  the  ore  which  would  fall  upon  it, 

before 


before  the  feparation  of  its  metallic  from  its  unmo 
tallic  parts,  would  leffen  the  fluidity  and  injure  the 
purity  of  the  melted  metal .  This  fcoria  ought  to 
have  a  certain  degree  of  fluidity  ;  for  if  it  be  too 
thick,  the  revived  metallic  particles  will  not  be  able 
to  -overcome  its  tenacity,  and  collect  together  into 
drops,  nor  be  precipitated.  Accordingly,  a  fcoria 
not  fufficiently  fluid,  is  always  found  to  contain  much 
metal.  If  the  fcoria  be  too  thin,  the  metallic  par 
ticles  of  the  ore  will  be  precipitated  before  they  arc 
fufficiently  metallifed,  and  feparated  from  the  earthy 
and  unmetallic  -parts.  A  due  degree  of  fluidity  is 
given  to  the  fcoria  by  applying  a  proper  heat  and  by 
adding  fluxes  fuited  to  the  ore. 

Some  ores  are  fufible  without  addition,  and  others 
cannot  be  fmelted  without  the  addition  of  fubftances 
capable  of  facilitating  their  fufion. 

The  fufible  ores  are  thofe  which  contain  fulphur, 
arfenic,  or  are  mixed  with  fome  fuuble  earth. 

The  ores  difficultly  fujible  are  thofe  which  contain 
no  mixture  of  other  fubftance.  Such  are  molt  of  the 
ores  which  contain  iron  in  a  Hate  nearly  metallic.  As 
iron  itielf,  when  purified  from  all  heterogeneous 
matters,  is  fcarcely  fufib'e  without  addition,  fo  the 
metal  contained  in  thefe  purer  kinds  of  ores  cannot 
be  eaiily  extracted  without  the  addition  of  fome 
fufibk  iubftance.  I.  Thofe  which  are  mixed  with 
fome  very  refractory  fubftance.  Some  of  thefe  re- 
fraftory  ores  contain  arfenic  ;  but  us  this  fubftance 
facilitates  the  fuiion  of  ores,  we  may  prefume  that 
their  refractory  quality  depends  upon  a  mixture  of 
fome  unmetallic  earth  or  other  infufible  fubftance. 
The  earth  which  is  mixed  with  the  common  calciform 
ores  is  in  confiderable  quantity  ;  and  is  fometimes  cal 
careous,  fometimes  filiceous,  and  fometimes  argilla 
ceous. 

Perhaps   the    fufibility  of   different   ores    depends 

greatly    oil  the   degree  of  calcination    to   which  the 

R  r  3  metal 


C    484    1 

metal  contained  in  them  has  been  reduced ;  fince  we 
have  reafon  to  believe,  that  by  a  very  perfect  calcina 
tion,  fome  metals  at  leaft  rruy  be  reduced  to  the  lia:e 
cf  an  eartk  alrnoil  unfuiible,  and  incapable  of  m:talii- 
fation  ;  and  fince  we  know,  that  in  every  calcination 
and  iubfequent  reduction  of  a  given  quantity  of  any 
imperfect  metal,  a  fenfible  part  of  that  quantity  is 
always  loil.or  cleftroyed,  however  carefully  thefe  ope 
rations  may  have  been  performed-  That  fome  of 
thefe  ores  are  already  too  much  calcined,  appears 
from  the  inilance  abovementioned  of  the  bo^  ores, 
\vhich  are  injured  by  reading  ;  and  even  the  great 
height  of  the  common  {melting  furnaces,  although 
advantageous  to  many  ores  that  require  much  roail- 
ing,  is  faid  to  be  injurious  to  thofe  which  are  ;; 
too  much  calcined,  by  expoiing  them  to  a  further  cal 
cination,  during  their  very  gradual  deicent,  before 
they  arrive  at  the  hotteit  part  of  the. furnace,  where 
they  are  fufed. 

But  as  too  violent  calcination  renders  feme  ores 
difficultly  fufible,  ib  too  flight  calcination  of  other 
ores  injures  the  purky  of  the  metal,  by  leaving  much 
of  the  fulphureous  or  other  volatile  matter,  which 
ought  to  have  been  e\  1  , 

Various  fukjiancts  are  a:'d  <.;'  ''  :frfi,,n  of  ores 

difficultly  fuli'.k*  Thefe  are,  i.  Ores  of  a  fuiible  qua 
lity,  or  which,  being  mixed  with  others  of  a  different 
quality,  become  fufible  :  accordingly,  in  the  great 
works  for  fmelting  ores  of  iron,  two  or  more  cfefterent 
kinds  of  ore  are  commonly  mixed,  to  facilitate  the  lu- 
fion,  and  alfo  to  meliorate  the  quality  of  the  iron.  Thus 
an  ore  yielding  an  iron  which  is  brittle  when,  hot, 
which  quality  is  called  rcd-Jkort,  and  another  ore  which 
produces  iron  brittle  when  col,!,  or  told-Jheftt  are  oi> 
ten  mixed  together;  not,  as  fometirnes  fuppofed,  that 
thefe  qualities  are  mutually  deftruciive  of  each  other, 
but  that  of  each  of  them  is  climiniihcd  in  the  mixed 
xnafs  of  iron,  as  much  as  this  mafs  is  larger  than  the 

part 


C    485    ] 

part  of  the  mafs  originally  pouefTed  of  that  quality. 
Thus,  if  from  two  ftich  ores  the  mafs  of  iron  obtained 
confiils  of  equal  parts  of  coki-iliurt,  and  of  red  {hort 
iron,  it  will  have  both  th  --.it  will  be  only 

half  as  cold Jksrt  <\s  iron  obtained  illely  from  one  of  die 
ere-:.,  and  half  as  red-jlort  as  iron  obtained  only  from 
the  <uher  ore.  i.Latils  andjic  es  are  all 6  generally 
ad  Jed  to  facilitate  the  fufion  of  iron  ores.  Thefe  are 
fuch  as  are  fuilble,  or  become  fuiible  \\iien  mixed  with 
the  ore,  or  with  the  earth  adhering  to  it.  Authors 
direcl:  that,  if  th's  earth  be  of  an  argillaceous  nature, 
limeftone  or  fome  calcareous  earth  fhould  be  added  ; 
and  that,  if  the  adherent  earth  be  calcareous,  an  ar 
gillaceous  or  filiceous  earth  fnould  be  added  ;  becaufe 
thefe  two  earths,  though  fingly  unfulible,  yet,  when 
mixed,  mutually  promote  the  fulion  of  each  other; 
but  as  limeftone  is  almoft  always  added  in  the  fmelting 
of  iron  ores,  and  as  in  fome  of  thefe,  at  IcaiVno  ar- 
gillaceous  earth  appears  to  be  contained,  we  are  in 
clined  to  believe  that  it  u  ,es  the  fu- 
iion,  not  merely  by  ui/V-  oarths,  but 
by  uniting  with  that  part  c  which  is  mofl 
perfectly  calcined,  and  leuft  di/po  ed  to  metallifation  ; 
iince  we  kr.ow,  that  by  mixing  a  calciibrm  or  roailed 
ere  of  iron  with  calcareous  earth,  without  any  inflam 
mable  m;;t;;er,  theie  two  ;  may  be  totally  vi- 
triried.  See  Expfnmmtt  ;.  ,::kllme  and  upon 
iron,  by  Mr  Brandt,  in  the  Sive  ijb  Mcw/trs  for  the  years 
1749  and  1751.  Calcareous  earth  does  indeed  fo 
powerfully  facilitate  the  fufion  of  iron  ores,  that  it 
defervcs  to  be  conlidered  whether  workmen  do  not 
generally  ufe  too  great  a  quantity  of  it,  in  order  to 
haften  the  operation.  For  when  the  fcoria  is  render 
ed  too  thin,  much  earthy  or  unmetallized  matter  is 
precipitated,  and  the  call  iron  produced  is  of  too  vi 
treous  a  quality,  and  net  fufficiently  approximated  to 
its  true  metallic  date 

Some 


Some  authors  pretend,  that  a  principal  ufe  of  ths 
addition  of  limeftone  in  the  fmelting  of  iron  ores  is  to 
abfc  rb  the  fulphur,  or  vi trie-lie  acid,  of  thefe  ores  : 
but,  as  we  have  already  obferved,  a  hepar  of  fulphur 
is  formed  by  that  mixture  of  calcareous  earth  and  ful 
phur,  which  is  capable  of  diiTolving  iron  in  a  metallic 
ftate  ;  and  thus  the  quantity  cf  metal  obtained  from 
an  ore  not  fufficiently  diverted  of  its  fulphur,  or  vi 
triolic  acid,  (which,  by  uniting  with  the  fuel,  is 
formed  into  a  fulphur  during  the  fmelting),  muft  be 
considerably  diminiihed,  though  rendered  purer,  by 
addition  of  calcareous  earth  :  hence  the  utility  ap 
pears  of  previoufly  expelling  the  fulphur  and  vi 
triolic  acid  from  the  ore  by  a  fuiricient  roalVing. 
3.  Tliefcoria  of  former  {meltings  is  frequently  added 
to  affift.  the  fufion  of  die  ore ;  and,  when  the  fcoria 
contains  much  iron,  as  fometimes  happens  in  ill-con 
ducted  operations,  it  alfo  increafes  the  quantity  of 
metal  obtained. 

The  quantity  of  thefe  fufible  matters  to  be  added 
varies  according  to  the  nature  of  the  ore ;  but  ought 
in  general  to  be  fuch,  that  the  fcoria  fhall  have  its  re- 
quifite  degree  of  thinneis,as  is  mentioned  above. 

The  fuel  ufed  in  mod  parts  of  Europe  for  the 
fmelting  of  ores  of  iron  is  charcoal.  Lately,  in  feveial 
works  in  England  and  Scotland,  iron  ore  has  been 
frnelted  by  means  of  pit-coal,  previoufly  reduced  to 
cinders  or  coaks,  by  a  kind  of  calcination  fimilar  to 
the  operation  for  converting  wood  into  charcoal,  by 
which  the  aqueous*  and  fulphure©ns  parts  of  the  coal 
are  expelled,  while  only  the  more  fixed  bituminous  parts 
are  left  behind.  In  France,  pit  coal  not  calcined  has 
been  tried  for  this  purpofe,  but  unfuccefsfully.  The 
life  of  peat  has  alfo  been  introduced  in  fome  parts  of 
England. 

The  quality  of  the  iron  depends  confiderably  upon 
the  quality  and  alfo  upon  the  quantity  of  the  fuel 

employed. 


E     4*7     J 

employed.  Charcoal  is  fitter  than  coaks  for  produ 
cing  an  iron  capable  of  being  rendered  malleable  by 
forging- 

The  quantity  of  fuel,  or  the  intenfity  of  the  heat, 
iriuft  be  fuited  to  the  greater  or  lefs  fufibility  of  the 
ore.  Sulphureous,  and  other  ores  eafily  fufible,  re 
quire  lefs  fuel  than  ores  difficultly  fufible.  In  general, 
if  the  quantity  of  fu?l  h  too  fwaJtt  and  the  heat  not 
fufficiently  intenfe,  all  the  iron  will  not  be  reduced, 
and  much. of  it  will  remain  in  the  fcoria,  which  will 
not  be  fufficiently  thin.  This  defect  of  fuel  may  be 
known  by  the  blackncfs  and  compaclnefs  of  the  fco 
ria  ;  by  the  qualities  of  the  iron  obtained,  which  in 
this  cafe  is  hard,  white,  light,  intermixed  with  fcoria, 
fmcoth  in  its  texture,  without  fcales  or  grains,  rough 
and  convex  in  its  furface,  and  liable  to  great  loljj  of 
weight  by  being  forged  ;  and,  laftly,  it  may  be  known 
by  obferving  the  colour  and  appearance  of  the  drops 
of  metal  falling  down  from  the  fmeltecl  ore,  and  of 
the  fccria  upon  the  furnace  of  the  fluid  metal,  both 
which  are  darker  coloured  than  when  more  fuel  is 
ufed.  When  the  quaniityoftbefuelisfiifficltntlylargffi 
and  the  heat  is  intenfe  enough,  the  iron  is  darker  co 
loured,  derfer,  more  tenacious,  contains  lefs  fccria, 
and  is  therefore  hfs  fufible,  and  lofes  lei's  of  its  weight 
by  beirg  forged.  Its  furface  is  alfo  fmocther  and 
fomewh;t  concave;  and  its  texture  is  generally  gra- 
nulr:ttd.  The  fcj-ria,  in  this  cafe,  is  cf  a  lighter  co 
lour,  and  lefs  denfe.  The  drops  falling  down  from- 
the  iihelted  ore  and  the  liquid  fr.oria  in  the  furnace 
nppcur  hotter  and  of  a  brighter  colour.  When  the 
quantity  (  f  fuel  is  too  great,  and  the  heat  too  intenfe, 
the  iron  will  appear  to  have  a  {till  darker  colour,  and 
more  ccnfpicuous  grains  or  plates,  and  the  fcoria  will 
be  lighter,  whiter,  and  more  fpongy.  The  drops*' 
tailing  from  this  fmelted  ore,  and  the  fluid  fcoria  will 
appear  to  a  perfon  looking  into  the  furnace  through 

the 


E 

the  blafl-hc-le  to  be  very  white  and  filming  hot.  The 
quantity  of  charcoal  necellUry  to  produce  five  hun 
dred  weight  of  iron,  when  the  ore  is  rich,  the  furnace 
well  contrived,  and  the  operation  ikilf Lilly  condud-jd, 
is  computed  fo  be  about  40  cubic  feet ;  but  is  much 
more  in  contrary  circumftances. 

The  time  during  which  tie  Jla'ul  rustnl  ought  to  Ic 
kept  in  j'ufon  before  it  is  allowed  to  nV>w  out  of  the 
furnace,  mull  alfo  be  ;•.  to*  H;.'W  long  that 

time  is,  and  \vho-Jicr  it  t  t •>  vary  according 

to  the  qu.  other  circumftances,  we 

cannot  determine,     in  ;  ,he  metal  is  al 

lowed  to  flow  out  of  the  furnacj  every  fix  or  c 
'ind  i  ry    10    or  12  hours.     Some 

works  i  hut  a  considerable  time  is  nccef- 

fary.for  the  concoction  of  the  mural.  This  is  cer 
tain,  that  the  iron  undergoes  feme  change  by  being 
I:ept  in  a  fluid  (late;  and  that  if  its  full  on  be  pro 
longed  much  beyond  the  ufual  time,  it  is  rendered 
lefs  fluid,  and  alfo  its  cohefion,  when  it  becomes  cold, 
is  thereby  greatly  dinnniilu-d.  The  marquis  de  Cour- 
tivron  fays,  that  the  ,1  may  be  reiiored  to  iron 

in  this  ftate  by  adding  to  it  forrie  vitreicible  eartli, 
which  he  confiders  as  one  of  the  conilituent  parts  of 
iion,  and  which  he  thinks  is  deftroyed  by  the  fufion 
too  long  continued.  That  the  fuftbility  of  caft-irou 
does  depend  on  an  admixture  of  ionic  vitrefcibleeanh, 
appears  probable  from  the  great  quantity  of  fcoria 
forced  out  of  iron  during  its  convention  into  malleable 
or  forged  iron,  and  from  the  lofs  of  fufi'oility  which  it 
fuffers  nearly  in  proportion  to  its  lofs  of  fcoria.  The  , 
quantity  ofirrn  daily  obtained  from  fuch  a  furnace  us 
is  above  defcribed,  is  from  two  to  live  tons  in  24  hours, 
according  to  the  richnefs  and  fuiibility  of  the  ore,  to 
the  construction  of  the  furnace,  to  the  adjuftnr. 
the  due  quantity  of  flu::  and  of  fuel,  and  to  the  (kill 
emplovsd  in  conducting  the  operation. 

The 


'ron  is  judged  of  by   obferving  the 
;  its  flowing  from  the  furnace,  and 
v.-he.i  it  is  fixed  and  cold.      If  the  fluid  iron,  while  it 
flows,  emits  many  and  large  fparkles  ;   if  rnany  brown 
fpots  appear  on  it  while  it  is  yet  red  hot;  if,  when  it 
is  fixed  and  cold,  its  corners  and  edges  are  thick  and 
rough,  and  its  iurface  is  fpotted  ;  it  is  known  to  have 
a  red-ihort  quality.      If,   in    flowing,  the  iron   feems 
covered  with  a  thin  glaify  craft,  and  if,  when  cold, 
its  texture  be  whitifh,  it  is  believed  to  be  cold-fhort. 
Mr  Reaumer  fays,  that  dark-coloured    caft    iron    is 
more  impure  than  that  which  is  white.     The  marquis 
de  Courtivron  is  of  a  contrary  opinion.      But  no  cer 
tain  rules  for  judging  of  the  quality  of  iron  before  it 
be  Forged  can  be  given.     From  brittle  call  iron,  fome- 
times  ductile  f  rged  iron  is  produced.     Cad-iron  with 
brilH.mt    plates    and    points,  when   forged,  becomes 
fomctimes  red-fliort  and  Ibmetimes  cold-lhort.     Large 
•;•;  plates,  large  cavities  called  ejes,  want  of  fuf- 
jficient   clenfity,  are  aimed  certain  marks  of  bad  iron; 
.  hcth:r  it  will  be  -cold  or  red  fhort  cannot  be 
be  forged.    Whitenefs  of  colour,  brit- 
leis  cf  texture,  and  hardnefs,  are  given 
any   cart  iron  by  fiidden  cooling;  and  we 
may  obferve,  that  in  general  the  whiter  the  metal  is, 
the  harder  it  is  alio,  whether  th^fe  properties  proceed 
from  the  r  or,,  or  from  fudden  cooling; 

and  that,  ;  dai'ker-coloured  iron  is  fitter 

for  being   caft    inM  i^ouljs.  bccau.e  it   is  capable  in 
ic-iTse  me.iRire  of  bciii:^  L 

after  it  has  been  expofed  during1 
red-heatii] 
cooled.     This   oper 

nettling,  chcMicvcs  the.  ti  .  ; 

fofter  and  more  capable  of  being-  filed  than  1 
and  al/b  cofflfide^ably  left  bnttle.. 

Mr  Reu  by  cementing  caft  iron 

with  i  i  a  red-heat,  the  metal  may 

2  be 


r  490  ] 

be  rendered  fofter,  tougher,  and  confequently  a.  fit 
material  for  many  utenfils  formerly  made  of  forged 
iron.  Whether  cementation  with  abforbent  earths 
gives  to  caft  iron  a  greater  degree  of  thefe  properties 
than  the  annealing  commonly  practifed,  has  not  been 
yet  determined. 

In  Navarre,  and  in  fome  of  the  foothern  parts  of 
France,  iron-ore  is  fmelted  in  furnaces  much  fmaller, 
and  of  a  very  different  conftrucHon  from  thofe  above 
defcribed.  A  furnace  of  this  kind  confids  of  a  wide- 
mouthed  copper-caldron,  the  inner  furface  of  which 
is  lined  with  mafonry  a  foot  thick.  The  mouth  of 
this  caldron  is  nearly  of  an  oval  or  elliptic  form.  The 
fpace  or  cavity  contained  by  the  mafonry  is  the  furnace 
in  which  the  ore  is  fmelted.  The  depth  of  this  cavity- 
is  equal  to  two  feet  and  a  half:  the  larger  diameter 
of  the  oval  mouth  of  the  cavity  is  about  eight  feet, 
and  its  fmaller  diameter  is  about  fix  feet:  the  fpace 
of  the  furnace  is  gradually  contracled  towards  the 
bottom,  the  greateft  diameter  of  which  does  not  ex 
ceed  fix  feet :  eighteen  inches  above  the  bottom  is  a 
cylindrical  channel  in  cne  of  the  longer  fides  of  the 
caldron  and  mafcnry,  through  which  the  nozzle  of 
the  bellows  paries.  This  channel,  and  alfo  the  bel 
lows  pipe,  are  fo  inclined,  that  the  wind  is  directed 
towards  the  lowed  point  of  the  oppoiite  fide  of  the 
furnace.  Another  cylindrical  channel  is  in  one  of  the 
fnorter  fides  of  the  furnace,  at  the  height  of  a  few 
inches  from  the  bottom,  which  is  generally  kept 
clofed,  and  is  opened  cccafionally  to  give  pailage  to 
the  fcoria :  and  above  this  is  a  third  channel  in  the 
£tme  fide  of  the  furnace,  through  which  an  iron  in- 
itrument  is  occafionally  introduced  to  ftir  the  fluid 
metal,  and  to  affift,  as  is  faid,  the  reparation  of  the 
Scoria  from  it.  The  greateft  height  of  this  channel  is 
at  its  external  aperture  en  the  outfide  of  the  furnace, 
and  its  fmaller  height  is  at  its  internal  aperture  ;  fo 
that  the  inflrument  may  be  directed  towards  the  bou 

torn 


C    49*    ] 

torn  of  the  furnace;  but  the  feccncl  channel  belotr  it 
has  a  contrary  inclin:«*iion,  that,  when  an  opening  is 
made,  the  fcoria  may  flow  out  of  the  furnace  into  a 
baibn  placed  for  its  reception.  When  the  furnace  is 
heated  fufficiently,  the  workmen  begin  to  threw  into 
it  alternate  changes  of  charcoal  and  of  ore  previously 
roafted.  They  lake  care  to  throw  the  charcoal  chiefly 
on  that  fide  at  which  the  wind  enters,  and  tlv;  ore  at 
the  oppofite  fide.  At  the  end  of  about  four  hours,  a 
inafs  of  iron  is  collected  at  the  bottom  of  the  furnace, 
which  is  generally  about  600  weight;  the  bellows  are 
then  ftopt  ;  and  when  the  mafs  of  iron  is  become  folid, 
the  workmen  raife  it  from  the  bottom  of  the  furnace, 
and  place  it,  while  y.-t  foft,  under  a  large  hammer, 
where  it  is  forged.  The  iron  produced  in  thefe  fur- 
nances  is  of  the  bed  quality  ;  the  quantity  is  alfovery 
considerable,  in  proportion  to  the  quantity  of  ore,  and 
to  the  quantity  »of  fuel  employed.  In  thefe  furnaces 
no  limeftone  or  other  lubftance  is  ufed  to  facilitate  the 
fufion  of  the  ore.  We  iliould  receive  much  inflriicliori 
concerning  the  fmelting  *of  iron-ore,  if  we  knew  up 
on  what  part  of  the  procels,  or  circumstance,  the  ex 
cellence  of  the  iron  obtained  in  thefe  furnaces  depends  ; 
v/hethcr  on  the  quality  of  the  ore  ;  on  the  difufe  of 
any  kind  of  flux,  by  which  the  proportion  of  vitreous 
or  earthy  matter,  intermixed  with  the  metallic  par 
ticles,  is  diminished  ;  on  the  forging  while  the  iron  is 
yet  foft  and  hot,  as  the  Marquis  de  Ccurtivron  thinks  ; 
or  on  fome  other  caufe,  not  obferved. 

The  iron  th'u>  produced  by  fmelting  ores  is  very  far 
from  being  a  pure  rnetal  ;  and  though  its  fuiibility 
renders  it  very  ufeful  for  the  formation  r.f  cannon, 
pots,  and  a  great  variety  of  utenlils,  yet  i;  want;  the 
itrength,  toughnefs,  and  malleability,  which  it  is  ca 
pable  of  receiving  by  further  operations. 

Call-  iron  fcems  to  contain  a  large  quantity  ofvitre- 
earthy  matter  mixed  with  the  pure  iron  ;  which 
is   probably    the  chief  caufe  oi  its  fufibiiity, 
S  f  brittlenefsj 


C     49*     ] 

brittlenefs,  hardnefs,  and  other  properties  by  which  it 
differs  from  forged  iron.  The  fulphur,  arfenic,  and 
other  impurities  of  the  ore,  which  are  fometimes 
contained  in  caft-iron,  are  probably  only  accidental, 
and  may  be  the  caufes  of  the  red-fhort  quality,  raid  of 
other  properties  of  certain  kinds  of  iroa :  but  the 
earthy  matter  abovementioned  fcems  principally  to 
diftinguiih  cafl  iron  from  forged  or  malleable  iron  ; 
for,  firft,  by  depriving  the  former  of  this  earthy  mat 
ter,  it  is  rendered  malleable,  as  in  the  common  pro- 
cefs  hereafter  to  be  defcribed  ;  And,  fecondly,  by  fu- 
fmg  malleabk  iron  with  earthy  and  vitrefcible  matters, 
it  lofes  its  malleability,  and  is  reilored  to  the  ftate  and 
properties  of  caft-iron. 

The  earthy  vitreous  matter  contained  in  caft  iron 
confifts  probably  'of  fomc  of  the  ferruginous  earth  or 
calx  of  the  ore  not  fufficiently  metaliifed,  and  alfo  of 
fome  immetallic  earth.  Perhaps  it  is  only  a  part  of 
the  fcoria  which  adheres  to,  and  is  precipitated  with, 
the  metallic  particles,  from  which  it  is  more  and  more 
feparated,  as  the  heat  applied  is  more  intenfe,  and  as 
the  fution  is  longer  continued. 

To  fep^arate  thefe  impurities  from  cad-iron,  and  to 
unite  the  metallic  parrs  more  clofely  and  compactly, 
and  thus  to  give  it  the  ductility  and  tenacity  which 
render  this  metal  more  ufcful  thin  any  other,  are  the 
effects  produced  by  the  following  operations. 

The  fir  it  of  thefe  operations  is  a  fution  of  the  iron, 
by  which  much  of  its  impurities  is  ieparated  in  form 
of  fcoria ;  and  by  the  fecond  operation,  a  further  and 
more  complete  feparation  of  thefe  impurities,  and  alfo 
a.  clofcr  compaction  of  the  metallic  particles,  are  ef 
fected  by  the  application  of  mechanical  force  or  pref- 
lure,  by  means  of  large  hammers. 

Some  differences  in  ihe  construction  of  the  frrge  or 
furnace,  in   which  the  fujinn  or  refin':n^  ofcaf.-'non'v'. 
performed,  in  the  method  of  conducting  the  opera 
tion,  and  in  oilier  circumftancesj  are  obferved  to  oc 
cur 


C     493     J 

ciir  in  different  places.     We  iliall  Jefcribe  from  Swc^ 
denborgius  the  German  me  thud. 

The  fatten  of  the.  c ail: -iron,  which  is  to  be  render 
ed  malleable,  is  perfornie  d  upon  tlu  hearth  of  a  forge 
iimilar  to  that  ufed  by  blackfmiths  :  at  one  fide  of 
this  hearth  is  formed  a  cavity  or  fire-place,  which  is 
intended  to  contain  the  fuel  and  the  iron  to  be  melt 
ed  :  this  fire-place  .is  20  inches  long,  18  inches  broad, 
and  12  or  14  inches  deep:  it  ia  bounded  on  three  fides 
by  three  plates  of  caft-iron  placed  upright ;  and  cr.  tlr; 
fourth  fide,  which  is  the  front,  or  that  part  nearelh 
to  which  the  workmen  (land,  by  a  large  forge-ham 
mer,  through  the  eye  of  which  the  fcoria  is  at  certain 
times  allowed  to  flow.  The  floor  alfo  of  the  fire-placs 
is  another  caft  iron  plate.  The  thicknefs  of  thefe 
plates  is  from  two  to  four  inches.  One  of  the  upright 
fide-plates  refts  againft  a  wall,  in.  an  aperUire  through 
which  a  copper-tube,  called  the  tuyere,  is  luted  with 
clay.  This  tube  is  a  kind  of  cafe  or  covering  for  the 
pipe  of  a  pair  of  bellows  placed  behind  the  wall,  and 
its  direction  is  therefore  parallel  to  that  of  the  bel 
lows-pipe  ;  but  it  advances  about  half  a  foot  further 
than  this  pipe  into  the  fire-place  ;  and  thus  gives  great 
er  force  to.  the  air,  which  it  keeps  concentrated,  or 
prevents  the  divergency  of  the  air  till  it  is  required  to 
act.  The  tube  refts  upon  the  edge  of  the  fide -plate 
which  leans  againft  the  wall,  nearer  to  the  back-part 
than  to. the  front  of  the  fireplace;  and  i^i  fuch  an 
oblique  direction,  that  the  wind  mall  be  impelled  to 
wards  the  fur  the  ft  part  of  the  floor  of  the  fire-place, 
or  where  this  floor  is  interfered  by  the  oppofite  fide- 
plate.  The  obliquity  of  the  tuyere  ought  to  vary  ac 
cording  to  the  quality  of  the  iron ;  and  therefore,  in 
every  operation,  it  may  be  fnifted  till  its  proper  pcfl- 
tion  is  found.  The  more  nearly  its  direction  ap 
proaches  to  a  hori/ontal  plane,  the  more  intenfe  is  the 
heat;  but  a  larger  quantity  of  fuel  is  confumed  than 
is  even  proportional  to  the  increafe  of  heat,  becaufe 
S  f  2  tllQ 


L     494     J 

llie  runnels  not  tile  nib  well  confined.  When  the  rrcfc 
Is  eafily  fumble,  great  heat  .is  not  required  :  the  tuyere 
rr:,iy  then  decline  considerably  from  the  horizontal 
plane,  and  thus  fuel  may  be  faved.  This  tuyere,  tho' 
made  of  copper,  a  metal  more  eafily  fufible  than  iron, 
is  preferved  frcm  fufion  by  the  ccriftant  paffage  of  cold, 
air  through  it.  It  muft  be  carefully  kept  open,  and 
clcanfed  from  the  fcoria,  which  would  be  apt  to  block 
up  its  cavity,  'by  which  not  only  the  heat  would  be; 
too  much  diniiniihcd  for  the  fuccefs  of  the  operation, 
but  the  tube  itfclf  would  be  melted, 

To  prepare  for  the  fufion,  a  quantity  of  fcoria  of  a 
former  operation  is  thrown  into  the  fire-place,  till  one 
third-part  of  this  be  full ;  and  the  remaining  two 
thirds  of  the  fire-place  are  to  be  filled  with  fmaller 
fcoT  la,  coal-duil,  and  fparks  ejected  from  hot  iron.— 
Thefe  matters,  being  fufible,  form  a  bath  for  the  re 
ception  of  the  iron  when  melted.  Upon  this  bed  of, 
iccriu,  the  mafs  of  carl  iron  to  be  melted  is  placed ; 
lo  that  one  end  of  it  fhali  be  within  the  fire-place ,  cp- 
pofite  to  the  tuyere,  and  -at  the  durance  of  about  four 
or  five  mclies  from  its  aperture;  and  the  other  end 
fuall  flancl  without  the  fire-place,  to  be  pufhed  in,  as 
the  former  is  melted.  The  iijr.per  fide  of  the  mafs  of 
iron  ou.|;ht  to  be  in  the  fame  horizontal  plane  as  the 
upper  p-rt  of  the  orifice  of  the  tuyere,  that  the  wind 
may,  by  means  of  the  obliquity  of  its  courfj,  (Irike 
upon  and  pafs  along  tlie  under-fide  of  the  mafs  ;  but  if 
the  Iron  be  difhcultly  fufible,  the  tuyere  is  to  be  dif, 
pofed  more  horizontally,  fo  that  the  wind  iliall  ilrike 
iiirecily  upon  the  mafs  of  iron  ;  and  that  one  part  of 
the  blaft  ihall  graze  along  the  upper  furface,  and  the 
olher  part  along  the  under  furface  of  the  iron.  The 
riiiifs  of  iron  \vcighs  generar.y  from  200  to  400 
pounds.  Sometimes  two  or  three  fmaller  mafTcs  a>e 
put  one  above  another,  fo  as  not  to  touch.  When 
thefe  are  of  different  qualities,  the  coid-fhoi  t  piece  is 
placed  undcrmoflj  that  being  more  unfuiiblc  than  the 

red 


L     4V5      J 

red-iliort.  The  iron  being  placed,  charcoal-powder  :* 
thrown  on  both  fides,  and  coals  are  accumulated  a- 
bove,  fo  as  to  cover  entirely  the  iron. 

The  coals  are  then  to  be  kindled,  and  the  bellows- 
are  made  to  blow,  at  fir  (I  ilowly,  and  afterwards  with 
more  and  more  force.  The  iron  is  gradually  liquefied, 
and  flows  down  in  drops  through  the  malted  fcoria  to 
the  bottom  of  the  fire-place  ;  during  which  the  work 
men  frequently  turn  the  iron,  fo  that  the  en  1  oppofed 
to  the  blaft  of  wind  may  be  equally  expofed  to  heat, 
and  uniformly  fufed.  While  the  coals  are  confumed, 
more  are  thrown  on,  fo  that  the  whole  may  be  kept 
quite  covered.  During  the  operation,  a  workman 
frequently  founds  the  bottoms  and  corners  of  the  fire 
place  by  means  of  a  bar  or  p:>ker,  raifes  up  any  mi's 
of  metal  which  he  finds  adhering  to  thefe,  and  expofes. 
them  to  the  greateil  heat,  that  they  m.iy  be  more  per- 
fetfly  fufed. 

When  all  the  iron  is  fufcd,  no  more  coa's  are  to  be' 
added ;  but  the  melted  m.ifs  is  to  remain  half  unco 
vered  for  fome  time  ;  during  which  the  iron  boils  and 
bubbles  and  its  ftirfice  fw.  11s  and  rites  higher  and 
higher.  When  the  iron  has  rifen  as  high  as  the  up 
per  edge  of  the  fire-place,  the  coals  upoa  its  farface 
mull  be  removed  ;  and  by  thiisexpoiing  it  to  cold  air, 
its  ebullidoa  and  fwelling  iubfiJe.  In  this  ftate,  or 
cocti  n,  the  iron  is  kept  during  half  an  hour  or  more, 
by  adding  occasionally  pieces  of  good  coal,  which 
maintain  a  fufficient  heat,  without  covering  entirely 
the  furface  of  the  mafs.  During  this  codion,  the 
workmen  allow  the  oriiice  of  the  tuyere  to  be  ha  f 
flopped  up  by  th«-  fcoria,  th  :t  the  air  may  not  blow 
upon  the  iron  with  all  ic-  force  by  which  it  would  be 
too  much  coded.  Accordingly,  when  they  thhktha*: 
the  coclion  has  continued  fuflicic;i.ly  long,  th  .  cl.ar 
the  paflage  of  the  tuyere,  and  the  mils  is  fo«  ,  4 

by  the   cold  air.     At  the  fame  time  aifo  they     p 
pa/Tige  in  the  eye  of  the  hammer  placed  in  the  fr< 


C 

of  the  fire-place,  through  which  forne  of  the  fcoria  i.i 
allowed  to  flow  out.  When  the  iron  has  become 
iblid,  the  bellows  are  ftcpt,  the  coals  are  removed,  and 
the  mafs  is  left  during  an  hour  ;  and  then  the  work 
men  raife  it  from  the  fire-place,  turn  it  upfide  down, 
and  proceed  to  the  fecond  ccction  or  fufioa  of  the 
iron. 

From  this  fecond  operation,  the  mafs  is  to  be  fo 
placed,  that  one  part  of  it  (hall  red  upon  the  tuyere, 
and  the  other  upon  the  fcoria  remaining  in  the  fire- 
place.  This  fccria  is  to  be  dijpofed  in  an  oblique  di 
rection  parallel  to  the  tuyere,  by  which  means  the 
•vhid  of  the  bellows  is  obliged  to  pafs  alung  the  under 
fide  of  the  mafs  of  iron.  About  the  fides  of  the  mafs, 
charcoal-powder  and  burnt  allies  are  thrown  ;  but  to 
wards  the  tuyere,  dry  and  entire  pieces  of  coals  are 
placed,  to  maintain  the  fire.  When  thefe  are  kindled, 
more  coals  are  added,  and  the  lire  is  gradually  excited. 
The  workmen  at'. end  to  the  direction  of  the  flame, 
.that  it  pafs  equally  along  the  under  furface  of  the  iron, 
quite  to  the  further  extremity,  .and  that  it  do  not 
efcape  at  the  ildes,  nor  be  reverberated  buck  towards 
the  tuyere,  by  which  this  copper  tube  might  be  melt 
ed.  During  this  fuiion,  pieces  of  iron  are  apt  to  be 
feparatecl  from  the  mafs,  and  to  fall  down  unfufed  to 
the  bottom  and  corners  of  the  fire-place.  Thefe  are 
carefully  to  be  fearched  for,  and  expofed  to  the  great- 
eft  heat  till  they  are  melted.  When  the  whole  mafs 
is  thus  brought  into  perfect  fuiion,  the  coals  are  re 
moved  ;  and  the  wind  blowing  en  its  furface,  whirls 
and  diffipates  the  fmall  remaining  pieces  of  fcoria  and 
fpurks  thrown  cut  from  the  fluid  iron.  This  jet  of  fire 
continues  about  leven  or  eight  minutes,  and  the  whole 
operation  about  two  hours.  In  this  fecoed  fufion  the 
fcoria  is  to  be  thrice  removed,  by  opening  a  paifage 
through  the  eye  of  the  hammer.  The  firft  time  of  re 
moving  the  fcoria  is  about  20  minutes  from  the  kind 
ling  of  the  fire*  the  fecond  time  is  about  40  minutes 

after 


C     497     3 

after  the  firft,  ai>d  the  third  time  is  near  the  end  of 
the  operation. 

The  mafs  is  then  removed  from  the  hearth,  and  put 
upon  the  ground  of  the  forge,  where  it  is  Gleamed 
from  fcoria,  and  beat  into  a  mure  uniform  lhape.  It 
is  then  placed  on  an  anvil,  where,  by  being  forged,  it' 
receives  a  form  nearly  cubical.  This  mais  is  to  be  di 
vided  into  five,  fix,  or  more  pieces,  by  means  of  a 
wedge  ;  and  thefe  are  to  be  heated  and  forged  till 
they  are  reduced  to  the  form  of  the  bars  com 
monly  fold. 

In  fome  forges,  the  iron  is  fufed  only  once,  and  in 
others  it  fuffers  three  fufkms,  by  which  it  is  faid  to  be 
rendered  very  pure.  Where  only  one  fufion  is  prac- 
tifed,  it  is  called  the  French  method.  In  this,  no  great 
er  quantity  of  iron  is  filled  at  once  than  is  iufficient 
to  make  one  bar.  The  fire-pla:e  is  of  coniideraby  lefs 
di mentions,  and  efpecially  is  lefs  deep,  than  in  the  Ger 
man  method  above  defer  ibed.  The  fire  is  alio  m-.re 
intenfe,  and  the  pioportion  of  fu.-l  confumed  to  the 
iron  is  greater.  The  iron,  when  melted,  is  not  kept 
in  a  ftate  of  ebullition  as  is  above  defcr;bed  ;  but  this 
ebullition  is  prevented  by  itirrii  t  the  fluid  mafs  with 
an  iron  bar,  till  it  is  coagulated,  and  becomes  folid. 

By  th^fe  operations,  fuflon  and  forging,  the  iron 
lojes  about  7?T  parts  of  its  former  weight,  fometimes 
more  aiid  fometimes  lefs,  according  to  the  quality  of 
the  call-iron  employed  ;  it  is  purified  from  the  vitreous 
and  earthy  parts  which  were  intermixed  with  it,  its 
metallic  particles  are  more  clofcly  compacted,  its  tex 
ture  is  changed,  and  it  is  rendered  more  denie,  foft, 
and  malleable,  tough,  and  dill-cultly  fufible. 

The  degrees,  however,  of  thefe  qualities  vary  much 
in  different  kinds  of  iron.  Thus  fome  iron  is  tough 
and  malleable,  both  when  it  is  hot  and  when  it  is  cold. 
This  is  the  belt  and  moil  uieful  iron.  It  m;iy  be 
known  generally  by  the  equable  furface  of  the  forged 
bar,  which  is  free  from  tranfverfe  Mures  or  cracks  in 

the 


[     498     ] 

the  edges,  and  by  clear,  white,  fm  all-grained,  or 
rather  fibrous  texture.  Another  kind  is  tough  when 
it  U heated,  but  brittle  when  it  is  cold.  This  is  called 
cold-Jbort  irr.n:  and  is  generally  known  by  a  texture 
confiding  of  large,  fhining  plates,  without  any  librcs. 
It  is  leis  ILible  to  ruft  than  other  iron.  A  third  kind 
of  iron,  called  red  JJjort,  is  brittle  when  hot,  and  mal 
leable  when  cold.  On  the  furface  and  edges  of  the  bars 
of  this  kind  of  iron,  tranfverle  cracks  or  fiflures  may 
be  feen  ;  and  its  internal  colour  is  dull  and  dark.  It  is 
very  liable  to  ruft.  Laftly,  fome  iron  is  brittle  both 
when  hot  and  when  cold. 

Moil  authors  agree,  that  the  red-fliort  quality  of 
iron  proceeds  from  fome  iulphur  or  vitriolic  acid  be- 
tjig  contained  in  it,  becaufe  fulphur  is  known  to  pro 
duce  this  effe<5t  when  added  to  iron,  and  becauTe  the 
iron  obtained  from  pyritous  and  other  fulphur  ate  d  ores 
has  generally  this  quality. 

The  caufe  of  the  cold-fliort  quality  of  iron  is  not  fo 
well  ascertained.  Some  imagine,  that  it  proceeds 
from  a  mixture  of  arfenic  or  ol  antimony.  But  this 
opinion  feems  to  be  improbable,  when  we  confider  that 
thefe  metallic  fubftanj es  may  in  a  great  meafure  be  dif- 
iipated  by  roafting,  whereas  the  ores  which  yield  a 
cold-fhort  iron  are  injured  by  much  roafting ;  that  no 
arfenic  or  antimony  are  obfervable  in  moft,  if  in  any, 
of  thefe  ores  ;  and  laftly,  that  thefe  femimetals  would 
render  the  iron  brittle  both  when  hot  and  when  cold. 
Cramer  and  other  authors  impute  this  vicious  qua'ity 
to  a  mixture  of  unmetallic  earth  or  vitreous  matter  ;  - 
and  affirm,  that  it  may  be  deftroyed  by  cementuion 
with  phlogifton,  and  by  f.;rging.  And  laiily,  others 
afcribe  the  cold-fhort  quality  of  iron  to  a  defcA  of 
phlo'gifton,  or,  as  Swedenborgius  fays,  of  fulphur.  To 
sifcertain  the  caufes  of  the  bad  qualities  of  iron,  and 
to  difcover  practical  remedies,  are  ftill  defiderata  ia 
metallurgy. 


L     499     ] 

In  one  bar  frequently  two  or  more  different  kinds  of 
iron  may  be  oblerved,  which  run  all  along  its  whole 
length  ;  and  fcarcely  a  bar  is  ever  found  of  entirely 
pure  and  homogeneous  iron.  This  difference  pro 
bably  proceeds  from  the  practice  we  have  mentioned 
of  mixing  different  kinds  of  ores  together,  in  the  fmelt- 
ing  ;  -and  allb  from  the  practice  of  mixing  two  or 
more  pigs,  of  cafe  iron  of  different  qualities  in  the  finery 
of.thafcj  by  which  means,  the  red-fliort  and  cold-iliort 
qualities  of  the  different  kinds  are  not,  as  we  have  al 
ready  remarked,  mutually  counteracted  or  ddlroyed 
by  each  other,  but  each  of  thefe  qualities  is  diminifh- 
ed  in  the  mixed  mafs  of  iron,  as  much  as  tins  mafs  is 
larger  than  the  part  of  the  mafs  originally  poiferTed  of 
that  quality  :  that  is,  if  equal  parts  of  red  fhort  and 
of  cold-lhot  iron  be  mixed  together,  .the  mixed  mafs 
will  be  only  half  as  red-fhort  us  the  former  part,  and 
half  as  cold  short  as  the  latter.  For  thefe  different 
kinds  of  iron  feemf  as  if  they  were  only  capable  of  be 
ing  interwoven  and  dilfuil'd  through  each  other,  but 
not  of  being  intimately  united  or  combined. 

The  quality  of  forged  iron  may  be  known  by  the 
texture  which  appears  on  breaking-  a  bar.  The  beft 
and  tougheft  iron  is  that  which  has  the  moft  fibrous 
texture,  and  is  of  a  clear  greyifh  colour.  This  fi 
brous  appearance  is  given  by  the  refinance  which  ihs 
particles  of  the  iron  make  to  their  rupture.  Ths 
next  be  PC  iron  is  that  whoie  texture  con  fids  of  clear, 
v.-hitifli,  fmall  grains,  inUrrrf  xed  with  fibres.  Thefe 
two  kinds  are  malleable,  both  when  hot  and  when 
cold,  and  h  ivi:  great  tc'iajky.  Ciil-fiort  irjn  is 
known  by  a  texture  confiding  of  large,  Ihining  plates, 
without  fibres:  and  red-fan,  iron  is  diiliiiguiflied  by 
its  dark  dull  colour,  and  ,b./  the  tranfverfe  cracks  .and 
iiffures  on  the  furface  and  edges  of  the  bars.  The. 
quality  of  iron  may  ba  mu.:ii  improved  by  violent 
comprefFion,  as  by  forging  and  rolling  ;  efpecially 
when  it  is  not  long  e;:pofed  to  tco  violent  heat,  which 

is 


C    500    3 

is  known  to  injure,  and  at  length  to  deftroy,  its  metal 
lic  properties. 

For  the  converfion  of  iron  mto  Jiee/9  fee  the  article 
STEEL. 


SECT,  VI.  Of  the  Smelting  of  Tin  Ores. 

THE  tin-ores  commonly  fmelted  are  thofe  which 
confift  of  calx  of  tin  combined  with  calx  of  arfenic 
and  fometimes  with  calx  of  iron.  Thefe  are  cither  pure, 
as  the  tin-grains,  or  intermixed  with  fpars,  (tones,  py 
rites,  ores  of  copper,  iron,  or  of  other  metals. 

The  impure  ores  muft  be  cleanfed  as  much  as  is 
poffible  from  all  heterogeneous  matters.  This  clean- 
fmg  is  more  neceflVy  in  ores  of  tin  than  of  any  other 
metal ;  becaufe  in  the  fmelting  of  tin-ores  a  lefs  intenfe 
heat  muft  be  given  than  is  fufficien"  for  the  fcoriiica- 
tion  of  earthy  matters,  left  the  tin  be  calcined.  Tin- 
ores  previoufly  bruiied  may  be  cleanfed  by  wafhing, 
fpr  which  operation  their  great  weight  and  hardnefs 
render  them  well  adapted.  If  they  be  intermixed 
with  very  hard  ilones  or  ferruginous  ores,  a  ilight  roail- 
ing  will-  render  thefe  impure  matters  more  friable, 
and  confequently  filter  to  be  feparated  from  the  tin- 
ores.  Som  times  thefe  operations,  the  roalting,  CKH.U- 
fion,  and  lotion,  mull  be  repeated.  By  roaiting,  the 
ferruginous  particles  are  fo  far  revived,  that  they  may 
be  feparated  by  magnets. 

The  ore,  thus  cle  mfed  from  adhering  heterogene 
ous  matters,  is  to  be  roaftcd  in  an  oven  or  reverbera- 
tory  furnace,  with  a  fire  rather  inte  ife  than  long  con 
tinued;  during  which  it  mult  be  frequently  itirred  to 
prevent  its  fuiion.  By  tht*  .operation,  the  arfenic  is 
expelled,  and  in  feme  works  is  collected  in  chambers 
built  purpofely  above  the  c-Jcining  furnace. 
•  Laftly,  the  ore  cleanfed  and  roamed  is  to  be  fated, 
and  reduced  to  ametall  c  .ftate.  In  this  fufion,  atren- 
tion  muft  be  given  to  the  f ollpwing  particulars,  i .  No 

more. 


[     5>°i     J 

more  heat  is  to  be  applied  than  is  fufficient  for  the  re 
duction  of  the  ore  ;  becaufe  this  metal  is  fufible  with 
very  little  heat,  and  is  very  eafily  calcinable.  2.  To 
prevent  this  calcination  of  the  reduced  metal,  a  larger 
quantity  of  charcoal  is  ufed  in  this  than  in  moft  other 
fufions.  3.  The  fcoria  muft  be  frequently  removed, 
left  fome  of  the  tin  fhould  be  involved  in  it ;  and  the 
melted  metal  mud  be  covered  with  charcoal  powder, 
to  prevent  the  calcination  of  "its  lurface.  4.  No  flux 
or  other  fubftance,  excepting  the  fcoria  of  former 
fmeltings  which  contains  fome  tin,  are  to  be  added,  to 
facilitate  thi  fufion. 

SECT.  VII.     Smelting,  of  Ores  of  Lead. 

'  ORES  of  lead  are  either  pure,  that  is>  containing 
no  mixture  of  other  metal ;  or  they  are  mixed  with  fil- 
ver,  copper,  or  pyrites.  The  me. hods  of  treating 
ores  of  lead  containing  filver  and  copper,  are  de- 
fcribed  in  the  fec~tior.s  of  Smelting  of  Ores-  of  Silver  and 
of  Copper  ;  and  in  the  former  of  thefe  an  inftance  is  gi 
ven  of  the  method  of  fme'ting  the  ore  of  Ramelfberg, 
\vl itch  contains  all  thefe  three  metal?:. 

Pure  ores  of  lead,  and  thofe  which  contain  fo  fmall 
a  quantity  only  of  filver  as  not  to  ccmpenfute  for  the 
expence  of  extracting  the' nobler  metal,  may  be  fmelt- 
ed  iii  furnaces,  and  by  operations  fimilar  to  thofe  ufed 
at  Rameliberg,  or  in  the  following  methods,  i.  From 
the  lead-ore  of  Willach  in  Carinthia,  a  great  part  of 
the  lead  is  obtained  by  a  kind  of  eliquation,  during 
the  roaftir-g  of  the  ore.  For  this  purpofe,  the  ore  is 
thrown  upon  feveral  ilrata  or  layers  of  wood,  placed1 
in  a  c-.ilcining  or  reverberator}"  furnace.  By  kindling 
this  wood,  a  great  part  of  the  lead  flows  out  of  the 
ore,  through  the  layers  of  fuel,  into  a  bafon  placed 
for  its  reception.  The  ore  which  is  thus  roalled  is 
beat  into  fmaller  pieces,  mid  expofed  to  a  fecond  opera 
tion,  fimilar  to  the  forrr.er,  by  which  more  metal  is 

eliquated  ; 


C    5^2    ] 

eliquated ;  and  the  retraining  ore  is  afterwards  ground, 
wafhed,  and  (melted,  in  the  o;d"mary  nietliod. 

The  kad  of  Willach  is  the  puroil  of  any  known. 
Schlutter  afcr;bes  its  great  purity  to  the  method  ufed 
in  extracting  it,  Ivy  wkich  the  mod  fuiible,  and  confe- 
quently  the  pureft  part  of  the  contained  lead,  is  fe- 
parated  from  any  lefs  tulible  metal  which  happens  to 
be  mixed  with  it,  and  which  remains  in  the  roafted 
ore.  This  method  requires  a  very  large  quantity  of 
wood. 

2.  In   England,    lead  ores  are  fmeltjd  either  up 
on  a  hearth,  or  in  a"  reverberatory  furnace  called  a 
cupel. 

In  the  firft  of  thefe  methods,  charcoal  is  employed 
as  fuel,  and  the  fire  is  excited  by  bellows.  Small 
quantities  of  fuel  and  of  ore  are  thrown  alternately 
and  frequently  upon  the  hearth.  The  fnfion  is  very 
quickly  effected :  and  the  lead  flows  from  the  hearth 
as  faft.  as  it  is  feparated  from  the  ore. 

3.  In  the  fecond  method  praclifed  in  England,  pit- 
coal  is  ufed  as  fuel.     The   ore  is  melted  by  means  of 
the  flame  pafling  over  its  furface  ;  its  fulphnr  is  burnt 
and  diflipated,  while  the  metal  is  feparated  from  the 
icoria,  and    collected  at  the  bottom  of  the  furnace. 
When  the  ore  is  well  cleanfed  and  pure,  no  addition  is 
requifite ;  but   when  it  is  mixed  with  calcareous  or 
earthy  matrix,  a  kind  of  fluor  or  fufible  ipar  found  in 
the  mines  is  generally  added  to  render  the  icoria  more 
fluid,  and  thereby  to  affift  the  precipitation  of  the  me 
tal.     When  the  fufion  has  been  continued' about  eight 
hours,  a  pailage  in  the  fide  of  the  furnace  is  opened, 
through  which  the  liquid  lead  flows  into  an   iron   ci- 
ftern.     But  immediately  before  the  lead  is  allowed  to 
rlow  out  of  the  furnace,  the  workmen  throw  upon  the 
liquid  mafs  a  quandty  of  flacked  qu  ck'ime,  which 
renders  the  fcoria  fo  thick  and  tenacious,  th  ;t  it  may 
be  drawn  out  of  the  furnace  by  rakes.    Schlutter  men 
tions  this  addition  of  quicklime  in  the  iineltino-  of  lead 


o 

ores 


[     503     ] 

ores  in  England,  but  thinks  that  it  is  intended  to  fa- 
cilitate  the  fa  lion  of  the  ores;  whereas  it  really  has  a 
contrary  erfeci",  and  is  never  added  till  near  the  end  of 
the  operation,  when  the  fcoria  is  to  be  raked  from  the 
furface  of  th6  metal. 


SECT.  VIII.      Of  the  Smelting  cfOres  of  Semi- 
mda1*. 

ANTIMONY  is  obtained  by  a  kind  of  eliquation 
from  the  minerals  containing  it,  as  is  de  c.'ibed  in  the 
article  ANTIMONY  ;  and  the  re  :,uius  of  an.imo.  y  is 
procured  from  antimony,  by  the  process  defended 
in  the  fame  article,  and  in  the  article  R  .G  zt/i  f  An- 
tim-jiiy. 

Arfenlc,  faffrs>  and  'lijmuth,  are  obtained  general 
ly  from  one  i.re,  namel) ,  that  cai.ed  c  I  <  t-  The  ar- 
feivc  of  the  ore  Is  fepara,eJ  by  roa  i  ng,  and  adheres 
to  the  internal  furfa  e  of  a  chimney,  wir.ca  is  ext'.ndid 
horizontally  about  200  or  300  feet  in  lengt'  s,  and  in 
the  fides  of  which  are  leveral  do  rs,  by  means  of 
which  tiie  arienic,  \>hjn  the  operation  is  fmilheJ,  may 
be  .wept  *>ut  ana  c  Heeled.  Thefe  chimneys  are  ge 
ne:  ally  bent  in  a  /,ig-'/ag  direction,  that  they  may 
bcL.er  ro  ar«l  an  1  Hop  ;he  arfenical  Howers.  Thefb 
flowers  are  ofvaii.^us  co  ours,  white,  grey,  red,  yel 
low,  accor  iir.'>;  to  tiic  q  i  .nt'ty  offulphar  or  other  im- 
pn  :y  wi  b  .  .  ippen  to  be  mixed.  Thjy 

arc  .it.  .c-i  oy  repeated  inblim,iiions  ;  while 

foni.-  -likame  or  oth.r  ^ab  lances  arj  added  to  detain 
the  .ulf hnr.:  an -J  t'<  a  Tnl  the  \  uriHcadon. 

In  the  lame  roaftihg  ol  5  which  t1  e  nrfenic 

is  expelcd,  the  b .f:^i;th  or  at  leail   Lhe  grcatell    j  art 
of  this  fernimcta'  which  is  conraiucd  in  the  ore,  ' 
very  fuiib'e,  and  having  no    di  p-»iition   to  nni.^ 
the    c.^uius  oi  crbult,  which  itinaias  in  the  ore,  is  fe- 
paraiea-by  eliquation. 

T  t  The; 


[     504     ] 

The  remaining  part  of  die  ro.ifbd  ore  confilts  chief 
ly  of  calx  of  regulus  of  cc  bah,  which  not  being  vola 
tile,  as  the  aifenic  is,  nor  fo  cafily  iufible  :4s  biimuth 
is,  lias  been  neither  vol utilized  nor  melted.  It  coutains 
aiib  feme  bifmulh,  and  a  fmall  Quantity  of  arfenic,  to- 
r  with  any  filver  or  o  her  fixed  metal  which  hap 
pened  to  l*e  contained  in  the  ore.  This  rcafted  ore  be 
ing  reduced  to  a  fine  powder,  and  mixed  with  three  or 
i'cur  times  its  weight  of  fme  fane1,  is  the  powder  called 
faffre  or  zcffre.  Or  the  malted  ore  is  fometirr.es  fufed 
\\iih  about  thrice  its  quantity  of  pure  fand  and  as 
much  pure  pot-nfh,  by  wliieh  a  blue  giais,  called//;/^, 
is  produced  :  and  a  metallic  maf?,  called  fpei/s^  is  col- 
Icded  at  the  bottom  of  the  vellel  in  vhich  the  matters 
are.fu  niUallic  mafs  or  fpeifs  is  compoied  of 

,  according  to  the  ccaitents  of 

the  ore  and  the  n:ethcv!s  cf  trejating  it.     The  matters 
.'..rent  times  are,  nickel,  regu- 

liiti  cf  ccba!t,  buh.uJi,  urienic,  fulphur,  copper,  and 
tilvir. 

Eifi.  "'.'rm  procured  from  any  other  ores  but 

that  (  .  might,  however  be  extracted  from 

res,  if  a  iuflicicnt  quantity  of  thefe  were 

iound.        I        /a-ie  method  by  which  it  is  obtained 

from       .  ly,  by  eliquationu 

.11  nati\e,  and  invclopcdin  much,  earthy 

fronj  '\'].i;]i  it  cannot  be  feparaieci 

it  IK  cl-ftilled  either  by  afcent  orby 

t.    When  it  is  mineralifed  by  fulphur,  that  is 

.,  is  contaii:eu  in  cinnabar,  feme  intj)  mediate  iub- 

as  quicklime  or  iron,  muft  be  added  in  the  di- 

Lon,  todif  ircm  the  fulphur. 

maden  in  Sp/ain  is  a   cinnabar, 

v,  i  h  '  it  ne  happens  to  be  fo  blend 

ed,  tl  .  is  requ'rcd  to  difcrgage  the  mer- 

r.      The  (  n  is  there  per- 

ibrnitd  in  :•         ace  c<hl  ,v,o  cu\itLsy  one  of 

which 


C    5=5    ] 

which  is  placed  above  another.  The  lower  cavity  is 
the  fire-place,  and  contains  the  fuel,  refting  upon  a 
gratC)  through  the  bars  of  which-the  air  enter^,  main 
tains  the  fire  and  paffes  into  a  chimney,  placed  at  one 
iide  of  the  fire-place  immediately  above  the  door  thro' 
which  fuel  is  to  be  introduced.  The  roof  of  this  fire 
place,  which  is  vaulted  and  pLrced  with  ieveral  holes, 
is  alib  the  floor  of  the  upper  cavity.  Jnto  this  upper 
cavity,  the  mineral  from  which  mercury  is  to  be  ciiltil- 
led  is  introduced,  through  a  door  in  one  ot  the  fides 
of  the  furnace.  In  the  oppoiite  wall  of  this  cavity  are 
eight  openings,  all  at  the  fame  height.  To  each  of 
theie  openings  is  adapted  a  file  of  aludels  connected 
and  luted  together,  extending  60  feet  in  length. 
1'hefe  aludels,  which  are  earthen  veflels  open  at  each 
end,  and  wider  in  the  rniddie  than  at  either  extremity, 
are  Supported  upon  an  inclined  terras  ;  and  the  aludel 
of  each  file,  tkat  is  moil  diftant  from  the  furnace,  ter 
minates  in  a  chamber  built  of  bricks,  which  has  two 
doors  av; J  two  chimneys. 

"V\  lien  the  upper  cavity  is  fi'.led  fufficiently  with  the 
miner  il,  a  fire  is  made  below,  which  is  continued  du 
ring  12  or  14  hours.  The  heat  is  communicated  thro* 
!cs  of  the  vaulted  roof  of  the  fire-place  to  the 
mineral  in  the  upper  cavity,  by  which  means  the  mer 
cury  is  \o".,  >nd  its  vapour  paiies  into  the  alu 
dels,  v  :  :-;h  of  it  is  condcufed  and  the  rdt  is 
difcharged  into  the  brick  chamber,  in  which  it  circu 
lates  till  it  alfo  is  condenfed.  If  any  air  or  fmoke 
pafTes  through  the  aludels  along  with  the  vapour  of  the 
mercury,  they  efcape  through  the  two  chimneys  of  the 
.-i'.  Three  days  after  the  operation,  when  the 
apparatus  is  iiifficieritly  cooled,  the  aludels  are  unluted, 
the  doors  of  the  chamber  are  opened,  and  the  mercury 
is  collided. 


THE  END. 


THE  UNIVERSITY  OF  CAUFORNIA  LIBRARY 


